Literally. Not to mention he barely knows this guy who won't be upfront with his feelings and is in a clear fwb relationship with. How are you supposed to trust someone that you've only known for a couple of months and only meet up every once in a while to fuck. Not even proper dates or anything. Kei realized he was developing feelings and distanced himself because he knew he couldn't keep up with such a vague relationship full of uncertainty. You can't blame someone for wanting more security in a relationship.
I understand that and I don’t blame kei for his trust issues but I feel like the ending is subpar…they didn’t have the conversation to explain everything and fix things. They didn’t even clearly communicate with each other. For me it feels like taiga was the one facing everything and blaming himself for not being clear while kei is also never explaining anything and still blames taiga for things…it just feels rushed…kei only made a move when he learned taiga was going abroad and cutting things off because that’s what kei said, “that he can never trust him” so it all feels rushed to whoop okay they made up whoop its all good now they’re together…..
People when someone has extremely bad past relationship experiences (taking advantage of him and even a married man using him??) so he now has trust issues and is now in a fwb relationship with an actor(people who ACTS?? Taiga's a professional one too) so now he's walking around eggshells around him bcs he doesn't know how much it'd affect him if something as sweet as Taiga's act towards him was fake in the end: