@tess14 Because it's really fucking hard.
I'm 36m and have my kids (7 and 9) most of the time. It seemed like most people in my dating-age bracket were single for very good reasons, had kids and expected any partner to fit into their life rather than give-and-take, didn't want to date anybody with kids (whether they had kids or not), or were at a point in their life where they were like "oh shit. the clock is ticking and I want to have my own kids" -- which wasn't great for me b/c I had a vasectomy for my ex-fiancee who dumped me just over a year later.
But I stuck to it, and started dating my girlfriend about a year after I dipped my toes back into the dating pool.
My best advice is just be happy with who you are, take care of yourself, do the things you enjoy, and keep looking. Join some meetups that are relevant to your interest and eventually something will fall into place. It's much better to wait for the right person then try to make something work with someone who isn't right for you.
You don't need someone who is self absorbed and needs you at their beck and call 24/7. You have kids. Their needs should always be your top priority. The right person will know that and support that.
Five years looking for the right person is better than 1, 5, 10, or 15 years with the wrong person.