I'm pretty sure I'm a lesbian, because girls never make me feel this way; but I do crave men sonetimes. However, when I get into a relationship with one, I am quickly turned off by something and end it. Little things like saying "I love you" too soon and serenading me to cheesy songs and expecting me to do all the work in bed just gross me out. Is this normal? Am I destined to only be happy with women?

Anyway, I wanted to share my logic behind why I think this mentality is totally healthy.
For me, I think it comes down to the fact that I think highly enough of myself to keep very high standards. Nobody would describe their ideal partner as someone who is lazy/selfish in bed, or too needy (saying "I love you" too quickly) or socially inept (not realizing that serenading a girl is generally always a foolish move unless you're vacationing in Spain AND you're, like, Usher during his peak in the early 90s). But many people are so anxious for the gratifying aspects of being in a relationship that they excuse a few negative traits for the sake of companionship.
I've always known that my ideal partner wouldn't make me feel uneasy, or act selfishly or embarrassingly, and that I deserve such a partner. So as soon as one of those tiny little turn-off warning signals surface, I peace out promptly.
Since I was 16 I've had a great two-year relationship and another wonderful four-year one (I'm 23 now). No other small ones though, just amazing long-term ones. And I think that's been because I ditch out when I see the smallest sign of something not sitting right, which has allowed me to remain free and open to get to know someone I'm truly compatible with.
I say: keep it up. Listen to your gut, and don't lower your standards. Be thankful you're the type of person who is independent enough to live that way! I'm sure you'll meet someone eventually who will only turn you on, and it'll be amazing.