Well, the main lead is a psychopath so I'd say he has never actually liked/been in love with anyone, maybe excluding the protagonist. I think you should give it a try!
That is not a good review what
we say psychopath endearingly
he does become very possessive of him especially later on in the novel
I don't know if you are looking for something more romantic, but like mc77 said, the main lead becomes very possessive later on which you can dress up however way you want lol. The relationship itself builds up slowly to that point, and you get a lot of both steamy and dangerous interactions between them. I personally enjoy how the plot doesn't jump to romance/sex at first sight. Lol this is a lot to say I hope you'll consider giving it a shot!
Try The Beast Must Die
Yo so someone recommended this but I don't read anything where the male lead isn't like, obsessed with the protagonist/only has eyes for him/has never loved anyone else.
I can read sexually promiscuous love interests but they can't have ever actually liked anyone else. Would y'all say this falls in that category? Thanks :)