What exactly is meant by "30+ years and without a girlfriend"? Are we talking about just anyone who is 30 or over and happens to be single or are we talking about being 30 or over without ever having been in a relationship? Quite a stark difference. I can't help but wonder if the latter is what OP was intending
Seriously, being in your 30s without ever having been in a relationship is worlds apart from being in your 30s and single after a break-up or divorce.
In any case, I think many people who have never dated are confused about relationships and frankly, so was I until I knew better. I too used to be confused about what "intimacy" meant. It goes far beyond what you find on 18+ websites. In fact, it is possible to get NSFW and have no intimacy at all. Intimacy is about being connected to the other person. You have intellectual intimacy where you can talk openly and deeply with your partner about things that interest or engage you. There is emotional intimacy where you can openly and vulnerably share your feelings with one another. Then there is affection -- you know, the cute and mushy stuff. And, of course, the NSFW things.
At this point, I believe intimacy to be what people are looking for. The thing is, one doesn't necessarily have to be in a relationship to have intimacy. In fact, it is entirely possible get find enough of it in friendships. The real question is how far. As far as intellectual and emotional intimacy between friends goes, I don't see why those couldn't go as far as romantic one would expect to find in romantic relationships if not further still. I can imagine a someone who is single getting by psychologically just fine with intimate friendships.
If one is in a relationship without much if any intimacy of any kind, that would make for a pretty shallow relationship at best and possibly toxic at worst. The same could be said about friendships void of even intellectual intimacy, let alone emotional intimacy.
But not being in a relationship and without any intimate friendships, or even worse, socially isolated? Now that is dangerous.