Knowing the potential of a relationship sometimes distracts us from the present status. Having someone who makes you happy most of the time but is very hurtful the rest of the time causes confusion. To stay with someone merely to have someone is the mistake a lot of people make. The way I see it, if they are cheating, lying, or not around half the time then you don't really have the person in actuality. Basically, you've closed the door for opportunity to find someone while the other person has had theirs open the whole time.