Your loved one betrayed you. You are damn angry on him/her.You fight with him/her.You scold him/her. You shout and you wish to never see that person's face again. But when you calm down, don't you wish to talk to him/her? Don't you wish to see him/her? Don't you wish to create memories with him/her again? Doesn't it hurt to see him/her talking normally with everyone but you? Doesn't it hurt that the person is smiling and laughing and you are not the reason anymore? Doesn't it?
Of course, it does
Because giving up feelings ain't easy
Feelings of love > feelings of hatred
There was a time when you were too attached to that person. It's hard to forget their betrayal but it's even harder to forget the memories you made with them.
Conclusion is try as much as you can not to get attached to anyone. You will get hurt but not more than that of getting betrayed by them. Prevention is always better than cure