Really. Their brains are broken and beyond that, I don't give a sh!t and I don't wanna know.
And I don't want to know what's going on in the brain of one guy when he "falls in love" with another because, their brains are broken.
Sexual love is how nature and/or God gets the person with the penis to put up with the person without one - and visa versa - for the purpose of having offspring. That's it.
I would also add to this precise statement that sexual love is nature's way of helping said persons stay married during the raising of those offspring. It's "God's gift to Man." Thank you. (And I'm an atheist!)