Well Scout, that is hard. In many ways you are fortunate because your s won’t remember all this. But in many ways, it is harder because your son is not yet verbal so you don’t know what is happening.
So, I had a live-in and he was not capable of caring for my then 11 and 9 year old sons. He hired babysitters to get “a break?!?!” I had zero help when he lived with me; he was a 3rd kid vs. a coparent. I was okay with it because I would rather do it all myself anyway as he was no sort of asset in this equation. (He now has 50% custody but often acts as a bestie more than a father. I think that is his guilt and wanting to be liked.). But he definitely is more responsible/involved than he was back in 2014. It took years.
My advice? Offer him an out and see what he says. I know it is optimal for two parents to be involved but sometimes both parents do not want to be involved. So, I would start there, but with no judgment.
Maybe start here (but only if you can be light and non judgmental) “Hey, is it me, or does this routine seem kind of hard?” Maybe this is too much right now with this early morning?” Then radio silence and see if he fights to see s1. If he is wishy washy, give him an out.
If he wants the nighttime routine with you there, I would take that in your home with you present. It is the safest option. If he wants an out, give it. If someone does not want to do it, it is best they don’t fake the funk. And this may be easier for you too, sadly.
You and s1 will be just fine. It just takes one parent. Look at Peace and Ginger and DNJ and Irish (who used to post here).
Me 41, H 47, M 15 yrs, S11, S13 BD 1: 11/4/14 we work on it; really I pretzel myself BD 2: 3/31/15 H goes down to "dorm room" 8/15: H back to MBR 10/15: H back in dorm room 1/18: H files, now divorced
