RpNation

which are?

Idea I have a list here https://www.rpnation.com/threads/looking-for-partners-longterm-au-oc-friendly.319951 though most aren't mentioned ^^

well, here are two immediate turn aways for most people that might otherwise want in:
*at least 18
*specific pairings

There are possible pairings, not specific. They're there there to show what I'd like but is never limited to just that.
As for age, apologies... I find it uncomfortable to RP with people much younger than me. I never know how to act; mosy topics I use in RPs would have to be limited and I dislike having to restrain myself. Sorry!

mosy topics? I hope you don´t mean there are sexual implications, given those are against site rules?

I do not roleplay explicit content on site; no. I might mention it though. No I mean very dark, psychological themes, emotional trauma, depression, suicide, gore and everything in between. Most of my roleplays are no sunshine and puppies; depends on my partner.

But nonetheless, RPing any kind of romance with a minor makes me uncomfortable.

I can tell you minors can handle that just as well as adults. In some cases, even better. But if it makes you that uncomfortable, I guess it can´t be helped. Though, it´s not that people don´t share your interests, it´s that many who do are getting shot out by the requirements
a large part of this site IS below 18

That may be so, but I do not think it is appropriate to RP such things with a minor. I one had a minor who wished to RP with me, using a character that is known for sadistic, necrophilic and pyromanic tendencies. I am NOT sorry saying that I do not wish to RP that with someone underage.
It is not about the minors; it is about my views, my comfort. As I said, I am sorry that you if you feel at disadvantage