You know, the comics are basically a soap-opera that's been running for over fifty years by now. And if a soap-opera goes on long enough, at some point all possible pairings will have been tried out at least once. The Avengers mostly have male members, and most of them are straight, so it goes without saying that the few female members will have to do the rounds to compensate.
But it seems rather silly to make a judgment of their characters due to story-telling limitations such as these.