Would you have forgiven the brother if you were in Jun’s place ?

definitely not. Couldn't even accept the fact that they were happy happy in the end.
Tho Jun said he willingfully accepted the sex with his brother it's still a forced sex. I don' even understand how you can be brother with someone by having sex. that is just beyond illogical.

sibling≠sex. never.

tho he is craving for brotherly love he should've at least have the sense of knowing what exactly a brother is.

and to dismiss what happened as just sibling spat... WOW

The end was a little messed up. I thought, Jun will break his "brother", and this way he can move forward.
I don't get, how could they become a cute brotherpair within a few panels...
Firstly I really liked the psychology behind it, but ind the end it was just not logical.