My ex husband had the kids this weekend and travelled to see them, I moved away (met someone else, and also his controlling and abusive behaviour didn't help). We usually meet half way but he offered. Didn't want to be accused of drip feeding 
So he came to visit and picked the kids up (great for us) and his girlfriend and her kids were meeting them there later.
On Sunday he ran a half marathon and was away from them for 5 hours, and left his girlfriend looking after them (which I have no problem with as she is lovely and I think she is great with them)
He sees them about every 3 weeks (his choice we would arrange to do more) and wouldn't see them that much more if we were closer anyway.
Yes it suited us for him to travel so I'm grateful for that, but it would have been nice if he wanted to spend the little time he had with them actually spending time with them, this is quite a regular occurrence and not the first time he's done this.
Maybe I am being unreasonable I just feel bad for the kids, and his girlfriend too.