I've started to realize that most people past 35 are low risk/low investment. They've had their lives, made their memories, and have no desire to retread familiar territory. If they're willing to socialize with someone new it's in a limited context only. They don't want the potential drama; They want familiarity, routine, to be comfortable.
This goes for almost everyone, not just those with children. For obvious reasons this isn't going to be enough for me.
Most of my "social" conversations with similar age people amount to not much more than surface level chat. There's no fertile ground left for enduring friendships, and the needy label gets applied fairly quickly if you're a guy and judged too keen to push things further. Suggesting something over the weekend is met with nonplussed reactions even from a so-called friend or "I need more notice" (a year?) Then the excessive planning required sucks most of the fun out of it.
Sure, they might down 10 pints at a bar if it's convenient but they don't want to do anything, and that's the problem here - it's been a problem for the last 7 years or so.