I don’t think it’s that mysterious. It’s like buying a house.
In younger adulthood, you are likely to rent. You are still working out your long term needs, and you are still laying the foundation (in this case saving for a down payment) to eventually do something more permanent. You will rent places that fit your immediate needs, without much concern about what’s ahead, knowing you can always move.
Eventually many people want to buy a house. At that point, they don’t need to spend years looking, because they already have a good idea of what they want and what’s available. There are plenty of houses out there, and once you know where to look for what you need, you’ll find one to fall in love with sooner than later.
The first paragraph contains a contradiction. Not feeling ready to settle down is a perfectly legitimate reason to abstain from long-term commitment. And it has nothing to do with “settling”.
If you’re at the stage in your life when your current residence is unlikely to be permanent (as is the case for many students and fresh graduates), then you tend to approach dating differently than someone who is physically anchored. Emotional entanglements can be a burden or they can be a blessing depending on life circumstances. The older you get, the more circumstances will support deep investments in other people.
After 30, I got more picky in dating partners, not less. It seemed my tolerance for incompatibility dwindled as my desire to find a marriage-track relationship increased. I think this is one of the reasons why dating is extra frustrating for people in their 30’s and 40’s. Not only has dating long lost its novelty, but with every person you rotate through, you realize how difficult it is to find someone who really clicks with you and doesn’t give you pause or reservations.
When you finally find that person and you’re ready to settle down, then not surprisingly, you will settle down with them.
I didn’t do that. I got into a serious relationship with my now-wife (at 23) because she was ready to settle down and it quickly became clear that somebody else worth keeping around was likely to see all she had to offer. Needless to say, that would have made our “friends with benefits” arrangement surplus to requirements. I was qiuite happy to settle down myself, as it turned out, though whether I was already there and didn’t know or “pushed” is a mystery. I waited another four years to propose and we married after five, so there’s that.
The move (500) Days of Summer (spoiler ahead, but it’s a 2009 movie) ends with Summer (Zooey Deschanel) leaving the boyfriend who has a serious crush on her and ends up marrying essentially the next guy she meets. Her lines (from IMDB) sum up what happened:
Sometimes it was just meant to be. At this point in her life she was ready for marriage, although for the rest of the movie she had adamantly scoffed at the idea. I think that happens in real life too.