It's because I'm pretty sure he'd want me all to himself, and I like him enough to give it a try, but I've never been with just one person — not without at least the option of others. While I'm not opposed to monogamy on an idealogical level, I'm scared of putting all my eggs in one basket, 'cause then if my heart gets broken, there's nothing to fall back on.

In short... it's both.