Hey Lao Che, good to see you!
Yes, you have to plan ahead. Everything in our society is "now now now! The future never comes!"
And then it's like getting hit with a freight train with the future shows up, for many people.
The good news is there's plenty of information out there.
So long as a guy's aware of his own end of history illusions he will generally be okay.
(but then again... a lot of guys are not...)
I'm in my late 30s now.
But I was married in my early 20s, divorced a few years later. So that's never been an issue for me. I've also basically never been single since I got into the game... always at least a girlfriend or two, and if need be I can talk about that with girls. They can typically sort of smell it on you also (and socially, for work functions, you just bring your girlfriend along, and everyone thinks she's great, and no one is worried about whether you're gay or a weirdo).
If you're worried about socially, just try to keep a few dateable FWBs in your rotation if you don't do girlfriends, and take one of them along when you have a happy hour or work party.
And if it's girls looking at you weird, just tell them you just broke up.
Technically if you are sleeping around a lot, it's like a lot of little breakups, all the time ;)
"We just broke up." --> "Oh I'm sorry, how long were you together?" --> "About 12 hours. She was great, but there wasn't any future there." --> "Oh I see."
There's the more serious route you can go, too.
Most guys have had a girl they were serious with, with whom it did not work out.
You can very easily use that girl as your story:
"I had a girl about 10 years back I was in a very serious relationship with. Then blah blah blah it didn't work out. I wasn't ready [or whatever the reason is. It should be you breaking up with her though]. And since then I've just been very busy and I'm only really getting back into more serious dating right now."
Typical tragic Byronic hero stuff.
That's going to be enough for most any girl.