Am I immune to hickeys (maybe NSFW)?

I’ll preface this with saying I know that this is a stupid question. But hey, I’m curious.

I’m 20 years old, and it seems like I can no longer get hickeys on my neck. I used to bruise there a ton, but also prior to the past six months had never been in a situation where I consistently got hickeys. A couple months ago though I noticed that although my partner would do the same things (sucking on my neck etc.) I no longer bruise there at all. The most I get is a few red dots for like a day.

I’m not necessarily complaining—they’re a pain to cover, but I’m just curious if skin that’s been bruised a lot can develop a sort of immunity? Like it’s not just a particular spot, it’s my whole neck. And I can get hickeys elsewhere on my body.