What I see is a lack of pride. I know we constantly push that it's a deadly sin, but in this case dignity means nothing to these types. They want all the benefits of being in a relationship (status, acceptance, common ground) but they don't want to take on the full responsibility of actually being the pillar of the relationship. This is so similar to people who cheat to win, so long as you're willing to commit to losing before you even take part, you win even when you know you failed. It's the coward's way out of facing life's struggles.