Could it be that you're looking for 'Neko x Neko'?
http://www.mangago.me/read-manga/neko_x_neko/
Oh lord IT IS AHDBDNF I THOUGHT THAT IT WAS A DIFFERENT MANGA SO I DIDNT THINK THAT WAS IT- when i saw neko x neko it reminded me of a different yaoi manga where both guys were cheated by this player and they got together instead to push away the player guy hhhh
Thank you so much!!!
Hahaha.. I mean I get why you'd think that given the title...
But no problem, hun! Happy reading! (≧∀≦)
Theres a yaoi manga where a strong guy goes out with a decently sized guy. The smaller guy loved him because he was so strong and after they went out, their body types changed since the frailer guy became a blue collared worker in construction and the buffer guy lost his muscle since he did more stationary work. But he gets self conscious about his lack of muscle and he tries to get it back by helping his boyfriend with his construction(?) work and works hard. But the thing is that since he lost his muscle and the other guy gained muscle, they switched uke seme roles. I think i read it on myreadingmanga but i cant seem to find it and it isnt an old art style like the 90’s or anything. I really want to reread it but idk where else to look since i dont remember any other prominent tags aside from reversible couple...
If anyone knows, please tell me!!