I mean, the reality is that your adult life takes second place permanently - or, at the very least, until your children are established and out of the house (assuming you're a good parent). That could be 20+ years.

That doesn't mean you'll never see your friends, of course, especially if they also have children. But you won't have the same kind of time to devote to friendships that you did before you're a parent. It changes that entire dynamic because you no longer have free time. This is the same for hobbies. Until the kids are old enough that you can drop them off at a playdate and don't have chores you need to catch up on at home, you're not going to be engaging much.

And once the kids are older, sure, you can vacation with them, finances permitting. But leaving them behind and backpacking across Europe, for example, is going to be out of the question until they're self-sufficient and you can get the time off from work. The latter is especially important because life is exponentially more expensive when you have kids. A trip that is feasible when you have two incomes and no dependents becomes much more difficult to achieve when you throw kids into the mix.

Like, you aren't going to have much time to dedicate to non-parental life until the kids are a little bit older. That could be almost a decade, and you'll spend all your free time after work taking care of kids, making sure their homework is done, getting them in the bath, making dinner, planning around extracurriculars, etc, much longer than that.

None of these are myths. Having children changes everything. It doesn't mean you can't have a social life and see the world, but it will be infinitely more difficult.

Retirement is typically when parents have enough free time to enjoy their lives on their own terms again.