I recognise some of the props and edit shots from some HIStory series. Taiwan really is a small industry!
I've seen a lot of Thai series and recognize various houses that get re-used also. For some reason I find that charming. I am just starting to notice it in Taiwanese series too.
This is tagged as gay on Gagaoolala and, despite being titled Close Friend Season 3, is entirely unrelated to the bl series Close Friend & Close Friend Season 2. To call this Season 3 is bait and switch. The only 2 romantic ties shown at all are straight couples. An elderly woman is very briefly revealed to have had a female lover in her past, and one character is barely shown to have realized he likes men, but he is not even out. Overall it is shameless opportunistic marketing to try to gain the bl audience for a completely non-bl series.
Pet peeve. Time travel where only one thing changes and other obvious changes that should have had big effects had no effect afterwards. I am writing this so as not to "spoiler" it--a main character's career should have been affected big time in the "new" future, but was not. MAJOR plot hole.
I generally don't watch the trailers for series because I like to see them without advanced expectations. I wish I'd watched this one. I'd have given it a miss for sure.
NOT open-ended, in my opinion.