
I don't think the seme cheated. I just think the timeline is not clear enough...
I think it should be something like this:
Seme meets the previous uke.
They get together.
Uke goes abroad for his career.
They split up.
Seme finds new uke.
They get together.
Previous uke comes back.
Finds out seme is with new uke.
Previous uke gets insomnia :/
If the seme made any mistake, maybe was not to be clear about breaking up or not... But it's not only his mistake but the previous uke too #-.-)...
And please, remember to separate reality from fiction (⌒▽⌒)
Just my opinion thought... And I will continue reading this because I love of sensei's works ٩(๑❛ᴗ❛๑)۶

Nice story and plot for the whole manga!! ٩(๑❛ᴗ❛๑)۶
But... Chapter 5, hmmm... It's pretty common in yaoi to end loving someone when they stop giving you attention so I'm fine with it. The thing that bothers me is that the black haired guy loves the ligh haired one even if the light haired one doesn't have the rash... Has the black haired one thought that maybe the blonde one will eventually get the rash?(╯°Д °)╯╧╧, because, man, he can also ve cheating on you, you know?! (︶︿︶)=凸

I absolutely LOVE Tanaka's sensei work!! This story goes beyond everything, it has deep feelings involved and you can totally feel the characters growth as the plot goes by. This is not just meaningless yaoi, this is full of emotions, just ABSOLUTE ART!!
Sensei is simply the best and I hope her whole work get translated and published in English (Spanish would be better for me since I'm Argentinian, but I think English would be more probable :P).
He got his pants wet anyway in the end xD