(I really do need to know, by the way.)
I have two DS aged 21 months and 9 weeks. We split for good a few weeks before DS2 was born and he has said he will do what he can to help me.
When he comes round to see the boys and to give me a hand I make the fatal mistake of asking him to play with DS1. ExH wants tojust "be" here, usually playing on his laptop or phone which he always brings.
In my eyes I think if the boys only see their dad a couple of times a week he should devote that time to them rather than see what's happening on the web. Also, I think as he has offered to help me (as DS2 is still v tiny and I dont sleep) that when I ask him to do things (eg take a box to the loft) that I shouldn't be met with "All you do is order me around." I do ask nicely.
I know that he has the right to parent his way. It just breaks my heart that when Daddy walks in the door DS1 runs to get train track/ball/whatever and is usually ignored after mins. I want to tell him not to bother coming but it isn't my place to say that.
And before you ask...yes the two were very much wanted by both (apparently) but he changed his mind as soon as we got pg with DS2. Family life was too "dull" for him.