It wasn't necessarily out of concern for my kids, it was mostly just me wondering if he did in fact behave differently when I wasn't around. I still wonder what he's like when I'm not around.
I'm not sure if it was limerence, I think it's mostly just a technique for testing boundaries. I know I've never been great at being supportive to a partner - and I told him as much - I think he just pushed to see how much he could get away with. He would do things like call me, even when it was my week with my kids, tell me something I had done hurt his feelings and he really needed to talk with me about it, and then push me to meet up. The talks would then usually take hours. And I, of course, thought I was just learning to be a better, more supportive partner, meanwhile he was teaching me to let him trample my boundaries.
Our youngest kids were like 11-12 and oldest were 17-18 (we had kids around the same age) so it wasn't like we were leaving small children at home but I hated when he would push me to leave them at all when it was my week. In addition, my kids hated it. His loved it because he was so controlling to them as well that they had time to breathe when he was with me.