Often when you go into a relationship with someone you like, you have to justify why you like that person. You only see what you want to see and you deny there are things you don't like about that person. You lie to yourself just to make yourself right. Then you make assumptions, and one of the assumptions is "My love will change this person." But this is not true. Your love will not change anybody. If others change, it's because they want to change, not because you can change them. Then something happens between the two of you, and you get hurt. Suddenly you see what you didn't want to see before, only now it is amplified by your emotional poison. Now you have to justify your emotional pain and blame them for your choices.
