Okay, I’m ignoring their behaviour as that isn’t the actual issue thats important here.
So you’re planning to leave with children who don’t actually know you, you’re a stranger to them. For you to do that would be a bit nuts, for their dad to be okay with it is insane.
Now, I’m no saint on this issue, I have done it quicker than a lot of people have. My son met my boyfriend in September (he was 4) and he had been hearing about my boyfriend for a while, seen a few pictures etc. We went from meeting at the park to him eventually coming round for lunch etc, to building up to over nights.
The master plan was for him to move in with us around October/November this year when they had known each other a year, a couple of holidays together and slowly building up how many nights he stayed over so it wasn’t a sudden change. By February we were upto two nights a week, sometimes consecutive and sometimes not.
Then in March we got symptoms of covid while he was here so he has to isolate with us for 14 days (his housemate has CF, so too risky to go home). It then meant after 14 days he either stayed here or we didn’t see each other at all until households could mix.
The first 14 days were okay, so I decided if he wanted to he could stay another week and I was reviewing it on a weeklg basis based on how my son was coping etc, if he wasn’t coping well and his he wasn’t his usual self my boyfriend would have been told to leave. It has generally gone well, it hasn’t been easy, there have been some very small bumps in the road. All routine etc has been based around my son and his needs.
We moved in too early, but it has worked for us, but to move in after not meeting one child and seeing the other one four times is insane.