bl where the other one is cold to everyone except to their lover

You should try 'The snake that swallowed the pomegranate'
It's the only I can think of right now, and it has an amazing storyline, plot and gorgeous characters
And yeah the Seme is uninterested in anyone else apart from uke but uke doesn't know that well enough.

I have some though some are a lot more mild than others https://www.mangago.zone/home/mangalist/2843251/