In that there are two sexes and it's implicit in any creation story that they're intended to mate. That simplicity has been clouded by religion leading to all kinds of spurious proscriptions, prohibitions and diktats about the circumstances in which that may take place. Ok the religions have all but gone but their traditions remain.

So mating has been surrounded by this thicket of commitment, expectation, individual responsibility, parental demands, the list must be endless. So, without a mate one can end up in that cultural forest alone and lonely. For those able to exist outside that set up they can enjoy mating and be alone otherwise. I don't see that as a problem.

There's quite some difference from being lonely and being alone.