My ex-husband has our kids, aged 8 and 10, over at his place every second weekend. He lives in an apartment where there is no special place set up for the kids, and they never feel happy about being there. When they get back home, it always seems like the transition is a difficult one, with me hearing every complaint and trying to make everything okay again. How can we make their relationship with their father more positive? They're at the stage where they just don't want to visit him anymore.
It is really normal for the transition between homes to be difficult for children, and for this conflict to be acted out in complaints and behavior problems. Any two separated parents have different parenting styles, and it is hard for children to make the adjustment between the two kinds of homes. I'm glad you are approaching it positively, wanting your children to have a relationship with their father rather than cutting them off from him or putting him down.
Is the lack of kids' space in your ex's home a temporary situation caused by a recent separation?
If so, it's probably temporary, and you or they can ask him to change his living situation so that his home feels like their home too. If it results from poverty, he can still have an area for them to keep some clothes and toys or can make the whole apartment "kid-friendly."
Listen to what your kids are saying. But unless he's abusive to them, it isn't your place to tell them either that their father is a wonderful man or that he is a jerk and that's why you divorced him. Let them find out for themselves the reality of who he is by observing his behavior. Be careful that your experience of this man doesn't lead you to subtly put him down to your children. Your ex deserves the opportunity to learn to be a good parent. Some people make terrible spouses but good parents.
Other people don't. If their father is just not "tuned in" to the needs of children, you won't be able to shield your children from this reality. They have to come to grips with it and grieve. Many parents don't like to see their children suffer, so they hide the reality of the other parent's inadequacy. This only postpones the grieving and confuses the children.
If your children's dad is not making his time with them positive, they are old enough to begin to tell him this, and to choose to reduce their time with him. You don't have to do this for them. Listen to them, and encourage them to tell him what they need in order to make his home an attractive place for them to be.