I think this is a deliberate choice, Anon! Aside from his first sexual encounter, I don’t think we really see Niall actually enjoying sex all that much. He has a lot of it and we see in episode 4 how it’s basically his only recreational activity. In episode 6 when he enters the bathhouse with Butch, he doesn’t seem super happy to be there? It’s his coping mechanism & after the break with Ava, one of his many self destructive outlets.

And since we never got to see what his relationship with Alby developed in the modern day, we don’t know how this has changed for Niall.

In another life, where he is braver and comes out earlier, this could’ve been completely different! He could still be a slut but one that enjoys it! And unleashes that mouth on his partners!

But instead he just has lots of sad sex with half of Glasgow.