
Of course, because it is so wrong for a romantic couple to have consensual sex!
╮( ̄▽ ̄)╭
That is the worst crime, and it is horrible that he broke up with her when she cheated on himヾ(❀╹◡╹)ノ~, and now she is dedicated to telling her current girlfriend about her sexual activities every time the ex has a chance to talk to the girlfriend(≧∀≦).
The fault is definitely his for having sex in the past(๑•ㅂ•)و✧!
(In case you haven't noticed, I've been using sarcasm, and I think he's a good boyfriend, have a nice dayლ(´ڡ`ლ))

Actually when I said they had sex in his house I moaned What if he manipulated her? I mean we already knew how he used manipulation and when she noticed that she just broke up with him.. But what if he use manipulation on her? Because you know she was not bitchy when they're first dated and very shy girl. But what if he used manipulation on her and she sleept with him because of that? When they're dated they were only 14-15. And in that age girls usually so easily manipulated by boys.. So.. What if.. He did that too.. Our MC 17 years old and have good friends which one easily can recognize about ML's games so he couldn't use so many manipulation on her.. But his ex didnt have any friends because of her beauty..

How you like to invent a whole paranoia to make ML the big bad guy in the movie.
The ML has not once manipulated the FL, neither has he lied to her, and if he has once done something suspicious he tells the FL right away, and lets her decide.
In my opinion he is a good boyfriend.
For me that you are projecting things in the ML, maybe in another type of manga you would be right, but here you are wrong.

Do you remember when he and his ex talked each other in the karaoke? She told him "because of you everyone run away from me. I felt like chocked.." he was a real manipulator and actually he told himself while tell to FL "I'm heavy". Some times young people cannot recognize that but if your partner block your social life and block other people's from you this means manipulation. He couldn't do that to FL because of her friends and her personality. Her personality didnt let him about use manipulation. Because even he didnt use any manipulation, she was already acted like how he wanted. Our FL's personality always put him on the center while do something or think something. So he even didnt use any manipulation on her. I saw that on the a blog and belive me.. Even Japans put him in "the top 10 manipulator ML list" themselves.
He is not a mind breaker but he is a manipulator. These things diffrent.

But that isn´t what the ML is doing, it is the opposite, it is always giving space to the FL, and fulfilling her wishes.
The ex just she wanted fool around with other boys while she had him as a boyfriend, and that didn't seem right to him.
And the ML isn´t manipulating the FL, as much as you try to believe that based on unsubstantiated evidence, he hasn´t blocked the social life of the FL to begin with (He has made friends with her friends), the closest thing to a social block was when he asked her not to approach a guy who showed that he had feelings for her and that he might make a move in her, in the end ML was right about it, but he apologized for being so heavy in FL .
And have a little more faith in the FL, it is true that she is very innocent and naive, but she has a voice for herself, and can handle its own relationship (In my opinion, both the ML and you and other readers, all underestimate the FL by putting it in the role of abuse victim).
He isn´t a manipulator, he is a very romantic boyfriend, and the FL can protect herself (Not to say that the FL tells everything to her friends, if something you say has the slightest chance of happened, the friends would be the first to know, and they would do something about it, but this isn´t a manga about abusive boyfriends, it is a manga about a very romanic boyfriend who already has marriage plans).
And the ex admits that she only wanted to be pampered by handsome guys all the time, and that's why she cheated on her, plus she hasn't stopped telling the FL about her sexual activities with the ML when they went out just to annoy the FL (Do you really think the ex is the victim of an abusive relationship?).
Yeah serve you right huh shitty ML? Your trash ex and your dirty past always make MC uncomfortable. I hate how he did EXACTLY SAME THINGS with his ex. He really need a big love rival for him