What's your experience with friendships?

Nothing romantic, friendships between divorced/single with no children, and married people with children? Do you find that there is more compromising and time expected from those who are unattached? Some of my friends would be even mad at me because I can have a good time, while they cannot have a drink, because they have to breast feed - their choice. I find myself babysitting, kinds reading their home works to me over the phone, me expected to spend more $ to travel to social gatherings, gifts. Some expect me to jump when they need me, since they don't think I got anything to do anyway, while when I would need a little compromise and help, sometimes they cannot do it for me, because they have family things to do.