We've all heard the terms, "rebound," "transitional" boyfriend / girlfriend, "tweener."

Relationships can be a tricky challenge when both parties are committed, and care deeply for one another. If one partner is just waiting for "something better" to come along, things can get pretty hurtful. Have you been, or are you now in a relationship with someone who seems to want to spend time with you only at his or her convenience?

There are several red flags you can look for. You never have meaningful conversations. He or she is tentative about making plans. You haven't met this person's family, or closest friends.

Click here for a list of 9 warning signs that you're just keeping the chair warm for someone else.