Koimonogatari - Vol. 2 Ch. 11

[MangaDex]

 

[LaDeeDah]

I knew it was coming but it still made me sad. I didn't even realize that I was kind of rooting for their relationship until they broke up.

 

[rlackbabbit]

He knewwww

 

[potatosaregreat]

...........

 

[qwqrd]

WHATTTTTTT I FUCKEN DONT UNDERSTANFFF

 

[notcishet]

The clues were if you look at all the times Yuiji and Mayu were together he's not smiling. Reading between the lines it seemed liking having a girlfriend was something he was expected to do (like schoolwork) while he really wanted to be spending time with his guy pals, especially Yamato.

TL: DR BL logic.