Why do I love people who can never love me back?

As a gay man, I am constantly falling in love with straight men. They are so masculine, and I love that in a man. I don't love straight men because they are straight, I love them because they are dominant and masculine on a level that no gay man I've ever seen can reach. But I am a man, and thus have no chance with them. Nonetheless, when I meet straight men I find attractive, I always fall for them and develop an unhealthy attachment to them. I tell myself I won't, I tell myself that I can control myself, but it seems like I just can't help it. I just grow so attached. I'm like a leech, except the host is the one who is doing the damage. I move from straight guy to straight guy, and the process is the same: fall in love with him, wish that someday he'll give me a chance, and another one will come along. I don't know how to help this. I can't think about any other person but the guy I'm currently trying to get with. It's very unhealthy, but I don't know how to stop myself, and it seems like I can't. Why do I get so attached only to people who can't love me back in the same way?