Long haul question

Hello! Little background on my story so far. MM and I met about 3 months ago. I was told his W has been cheating. We met pretty much by chance and decided to explore a casual fwb situation. Both of us have caught feelings but he is not interested in leaving at this time due to the kids. I have never had any ideas that this would turn into a legit relationship. I love my independence and ability to do my own thing while also enjoying the connection we have. Neither of us sees this ending any time soon.

That being said, my question is for the long -haulers out there. How has your relationship evolved? How do you feel you’ve made it work?