I'm neither a vet nor a psychologist but I'll give my opinion. First of all, I would like to ask,

1) Is he strictly a house cat, meaning that he's never been outside before?
2) Is he the only cat in the house?
3) Does he never have contact with other cats?

If the answer is yes, then probably it's a sign that he's lonely/depressed/just need more attention from you or probably what he needs is another companion from his own kind.   Try experimenting a bit for example try bring in your friend's cat just to see his reaction.

As for cats getting horny, from my experience  the first sign that you can see is that your cat started to 'mark his territory'. After that he will regularly do the unusual 'meow' sound, more like 'mauuuw' sound. This only applies to male cats only. If you've seen documentaries about lions or cats mating, it's almost the same. You get the idea.

As far as I know, there are no Gay or Lesbian or Bi in pets/animals.

Those are purely human behaviour, not pets/animals.


KP

Is he once a stray cat? If so I suggest that everytime when you bring some food to him, maybe you could stay with him while he's eating and while he's at it, always touch him and try to communicate with him a bit. It probably needs time and patience to get his trust because he maybe have some bad experience with humans before.

Using fluffy things is also a good idea. Maybe you could make something like a short fishing pole except that the bait is that fluffy thingy and try to lure him out from his hiding place. After that you just play with him like that, no need to grab or cuddle him because he may feel uncomfortable. Oh yeah, forgot to mention, while playing with him try to intentionally put the bait near you once in a whle. Maybe that way it can reduce his shyness to people.

Ganbatte...