I can't stop cheating on my significant other
Did the other person come unto you?
I don't think it's my fault
It is hard to resist temptation but you shouldn't cheat on a partner. It is hurtful and it could lead to breaking up.
I've been cheating on my girl for a long time and I don't get it.
If that's the case, why not try putting yourself in your significant other's shoes? How would you feel to be constantly cheated on? I feel it's the best to come clean and break up, so both of you can have a clean start with someone else.