Make a list of all the things you do that aren’t natural. How many things do you engage with that are purely for comfort or pleasure? I don’t agree that love only exists for reproduction. If we lived forever and never needed to reproduce, we’d still have love for family, friendship, hobbies, etc — so why not romance?  Gay attraction is not chosen. It happens naturally in a percentage of the population — it comes from nature. Even if you view reproduction as some form of perfection, nature routinely produces things that deviate from perfection. Nature is imperfect.