In episode 7, the SML and SFL have a sexual relation but the SFL was obviously drunk and He seems that he wasn’t. Am I the only one who thought it kinda of weird? Or I’m just being too detailed?

I agree with you, and in the same time, I don't. which is why in my opinion nobody wanted to share their ideas.

not interacting with someone drunk is to protect the drunk person from doing something he/she wouldn't have done in normal situation: they don't love you, but they have revenge sex with you because they were disappointed with their lover (that's why they drunk), and obviously, they will regret it afterwards. in this situation, ok, that's so bad.

why I disagree: she was drunk but she was the one who initiated the relation, and it wasn't caused by the alcohol intoxication. she wanted to be with him and hold back as long as she was sober.

he did nothing wrong, he was the one pushing her away for social reasons, and was also holding back because he loved her. that's absolutely understandable that he let his real feeling take control when she confessed her love.

she seemed to take a very active part in the sexual intercourse. it's not like she couldn't even move properly as she is the one taking off his clothes.

why I agree: you never know in this kind of situations and he could have just kissed her, even being nude and sleeping together without going all the way trough the sexual intercourse. the meaning would have been the same and they would have saved their first time for a more sober and conscious experience.

and now she doesn't remember her first time with him...

it's not something moral or ethical here, because they 2 were clearly consenting to the same thing. it's a relational pass: their first time is ruined forever.

you are cute...

 Han:

The reason that sleeping with someone while they're drunk is immoral is that you can't give consent when you are drunk. Whether or not SFL initiated, SML has a responsibility to deny her until she is sober. 

In this particular case, both parties (while still sober) consent to drinking (as a twosome) and long for intimacy with the other. There's no indication that their sober selves would not still consent to intimacy thinking of their future drunk selves. They only tell each other about their mutual interest when at least the SFL is drunk, but their respective consent I'd say was formed well before that.