I'm of the lesbian persuasion, so in my case, would I date someone of the opposite sex for sake of happiness? I suppose it is possible.
I've known a few lesbian women to find love in a man, and they admit they never thought it possible. One girl was such a rampant lesbian, she drew comics and became kind of a icon for gay women. Then she moved to california, and I lost touch with her sort of her comic diary. Turns out, she fell in love with a brit, and was as shocked as everyone else!
My own lifes long love interest was married to a military man. She at one time confessed to wanting to have his baby one day.
I personally am most attracted to women. I like to hang out with guys now and again, but I don't find myself attracted to them. It's more than the genitalia, too. Guys are hairy, abrasive, and carry all the wrong energy. It's enough to shut down all attraction. I know an attractive guy when I see one, and cam woman enough to admit seeing what a girl might find attractive. But even if you shave him smooth, give him a soft touch, you can't change that male energy.
I won't say it'll never happen. But it's just not likely.