(Baby don't hurt me...don't hurt me, no more.)
Anyway there are many real and would-be real couples in the RE series. The happy family of William and Anette are a good example of a real couple.
But what most fans prefer to think and theorize and write fanfics about are the would-be/should-be/could-be couples. The most prominent are of course Leon/Ada and Chris/Jill. There are obvious suggestions towards the former but as far as I know, nothing at all hinting towards the latter.
One couple I always fancied was Rabecca and Billy... I dunno. I just thought they looked cute together and the RE0 ending was my favorite RE ending.
But what about you? Do you support any fan couples?