The Legends   (2019 chinese drama)

- guy crazy in love for years, jealous and protective

- strong female lead but clueless when it comes to true love

- there is a second (and even third) male lead who has great chemistry with FL, but it's clear from the beginning he has no chance with her, instead he provides a reason for jealousy

Chijo no Kiss 

I just finished watching, and I think it matches your description pretty well 

I've created a list of my own on this topic: https://kisskh.at/list/47ay78AL
Hope it would be helpful. 

Time to fall in love

https://kisskh.at/697853-love-from-zero-to-one: Link to fall in love (2022)

Love is sweet

 fanitha:
  • Sekai ichi muzukashii koi
  • Well intended love
  • High end crush
  • Secret Garden
  • The greatest love
  • Pin to Kona
  • Hana yori Dango
  • Takane no Hana
  • When the Camellia blooms

Taking no Hana so their are 2 drama with this title one is in2018 and other in 2019.. which is the correct one

 Gauri:

Taking no Hana so their are 2 drama with this title one is in2018 and other in 2019.. which is the correct one

There's just one the other is "Takane TO Hana". The on I suggested is Takane NO Hana 

https://kisskh.at/29285-takane-no-hana

Please guys recommend more dramas

Some more dramas where the ML chases first and for a long time and is a little crazy about it: 

Please guys recommend more romance dramas with madly in love male leads 

  • The Best Thing : On the cute way, respecting all her boundaries. No red flag more like a green forest type of madly in love ML
  • Bon Appetit, Your Majesty : Romance isn't the main focus here and I wouldn't say he is madly in love but he is very obsessive and in the end falling in love though as I said romance is a side plot
  • Go Ahead : He basically loved her since childhood and is waiting for the right time to chase her. Once he thinks it's time, well there is no shame anymore lmao. I guess he is the most in love man I saw in a drama but it is a respectful, heartwarming love. Nothing with toxcity here. 
  • Love and Redemption : He basically would do anything for her and when I say anything it is. No self esteem or dignity when it comes to her. She is quite cold to him (for some plot reasons) but when the plot unwraps it makes sense. Madly in love, yes
  • Story of Kunning Palace : The longest slow burn I've ever watched tbh though he is CRAZY  and obsessed with her. He did things to her that are toxic but not for love purposes. It is quite complicated but really deserve a try
  • When Destiny Brings the Demon : I would not say madly or crazy in love but she is surely everything to him. He would not hesitate to go berserk for her or sacrifice what he needs to. I guess he has a soft spot for her since their first meeting, imo
  • The First Night with the Duke : He goes crazy for her once they spent a night together. He wants to marry her but she won't. He is quite obsessed about her but in a cute and respectful way
  • Love Better than Immortality : He is the villain and very obsessed with her. At the beginning it is not because he loved her but over time it is becoming another time of obsession
  • Coffee and Vanilla : Fowardly obsessed guy but he is quite toxic but this is romantized
  • Hua Jai Sila : He is obsessedddd but cannot give it in. Toxiiiiic boy but I guess he is trying his best but for revenge purposes he has to make choices that hurt FL emotionally. Though he can be involved with other women, he cannot bare the idea of her with another even if they are not together

So many good titles already, I'm sure to repeat some of the ones already mentioned. But anyway, here are my favorites for an extremely loving ML who loves an FL who is slow to catch on. These are dramas where there may be competition for the FL, but the 2ML wouldn't be in the running if the FL weren't clueless about her own feelings. I love I Hear Your Voice, too, and I think it's one example of the FL dating the 2ML because she's trying to resist her feelings for the ML.

Amidst a Snowstorm of Love - he falls for her at first sight, and has no brakes when it comes to loving and giving (and spending money on her), but he is awkward, so it's understandable that she doesn't catch on at first. There is no second male lead, although later there are a few scenes of jealousy over an unimpressive would-be rival. This drama is excellent, and it doesn't have a ton of distractions. There's an ensemble, but a lot of what they do is to provide a chorus of admiration for the leads' relationship. It's that darling trope, "The World Is Your Wingman."

Love Like the Galaxy Part 1 and Love Like the Galaxy Part 2 - what can I say? Wu Lei is awesome at playing super devoted male leads who are hyperfocused on the female lead. However, I have to warn you, there's stuff going on besides the relationship, like mega obstacles. And there is a temporary second male lead. And a squad of nasty, high born, second female lead wannabes (but it's fun watching them get shot down, IMO). And it's a very slow burn. But General Ling Buyi repeatedly rescues Cheng Shaoshang, even before they are together, and those rescues definitely heat things up. Also, he's extremely steadfast and vocal in the face of her detractors - and there are a lot of detractors, including her parents. So to sum the devotion part up, Ling Buyi has many opportunities to show love through acts of service, and he never misses an opportunity. When it comes to the FL's cluelessness - she's young when they first meet - so she's unable to recognize the potential for a passionate, full bore, military specs adult relationship. One of many lovely things about this drama - he respects her process of awakening, and her choices.

Bromance - Okay, this has its dorky moments. But the chemistry is TO DIE FOR,  the ML is 100% devoted, and the FL is attracted, but is insecure, and you could even say clueless, about how much the ML is into her. And there is no competition. She's lived her whole life pretending to be a boy, and the drama uses that to prolong her uncertainty -- she can't ask him because she's pretending to be a guy. There are two supporting couple lovelines, one tender and a little melo, the other farcical, and these are also competition-free.

Romance Is a Bonus Book - There's a second male lead, but because all the characters are really realistic and detailed, the interactions between the 2ML and the FL don't feel like a distraction. What they feel like is what you are asking for - the female lead's cluelessness. In this case, the FL can't quite grasp the fact that the dongsaeng has matured significantly since they were childhood friends. So when the second male lead starts courting her, she's flattered. As in I Hear Your Voice, Lee Jong Suk again uses his acting superpowers to portray a green flag ML who is crazy in love. His character in RIABB has a track record of over a decade of (hidden) devotion to the FL.

One Spring Night - She's halfway out of a previous relationship when she meets the ML. But her soon-to-be-ex is no second male lead. Her ex is one of the problems the couple have to battle against. In this drama, the leads don't fit the template for society's ideal relationship. The ML is not rich, and he has a kid. The FL is older than the ML, and has to extricate herself from her privileged lame duck boyfriend. This drama is a bit more realistic than most romances, yet it's very romantic.

The reason I recommend it for you because (1) the ML is a major green flag, (2) their chemistry is awesome, and (3) the ML takes a risky chance by pursuing her. (It's brave of him, given his social status.) And when she wavers, he delivers trust and confidence. However, I must admit, she's not clueless. But while she's aware of her attraction to him, she is at first hesitant about going further. And there's some tension, because her ex feels entitled to refuse the breakup. However, the core of your request - a remarkably loving ML, a love line that is strong and vibrant, a strong focus on the relationship - the drama absolutely delivers. This ML is a good man - nurturing, passionate, and sensitive. But butch enough to not get friend zoned. :)