I'm in this situation too. It's not easy. Been together 7 years now, and we see each other half a weekend each fortnight (when child free). We're both mid 40's and live about 15 minutes away from each other. We only see each other at DP's house, also because of her pets. But beyond a toothbrush I don't keep anything else there.
Our kids were all primary age when we got together, now they're all tweens and teens. I thought it would get easier as the kids got older, but it's actually made our relationship harder. We used to do activities, days out, holidays all together, and the kids mostly got on great (we met through some of our kids being friends). Now one of DP's teenage kids doesn't like us all mixing together (seems like the competition for attention is his issue), so that's scuppered us doing anything as a group. Which means we see less of each other than we used to.
Also, the kids getting older means they have more hobbies and interests that take priority over us seeing each other. For example, if one of our kids has a sports event on, we can end up swapping our child contact arrangements with our ex partners, and so our one weekend child free together gets scuppered. Sometimes it feels like we only see each other when the stars align, longest that's been was nearly 3 months without even catching up for a coffee. I dearly long for us to have more of a relationship and spend more time together, but I know that kids take priority.
I think what always kept me going was the light at the end of the tunnel - the idea that when the kids all reach adulthood that we'll live together as a couple (at the outset I thought we might even be able to blend and live together sooner). But I think that light is gradually fading rather than getting closer. Adult kids probably aren't going to all just disappear off into the world and do their own thing at 18-20 years old.
But the bigger thing that seems to be emerging is that our kids being friends and similar ages are the biggest thing we have in common. Take them out of the equation and our likes and interests look completely different.
We're also both quite independent, so while living together seemed like a dream, I'm starting to think the reality of it might be completely different, especially as by the time our kids are adults, we'll both have got very accustomed to our own space.
I think the longer it goes on, and the more my end game seems to be slipping away, the more I'm feeling like it's actually just a situation ship - companionship that works for our current circumstances, but I suspect won't last once our kids are grown up. Which is somewhat sad and depressing, but even more so because I think that's always how my partner has seen it from the outset.