Do you ever ask for favours (real favours, not pretend ones, things that actually HELP you and not make your 'friends' feel better)? If not, why not?
Because I'm a SAHM, and with a DH who travels a lot, I help out friends who work when their regular childcare falls through (CM, so ill children etc) or they have to work extra hours, but they do favours for me too, I have DC at different schools so if I want to go to one of their activities, they pick up the other DC from his school and keep him for a few hours.
Another friend has become a closer friend since we have started swapping favours, I have her DD after school to give her a few extra hours to focus on her work, and she or her DH will often take my DS to sports activities on the weekend when they clash with my other sons' as our boys are on the same team.
It all works because we swap favours so often, but as others have said, the boys are friends, and we are friends. We're all very careful not to take the piss, and all genuinely appreciative of the favours. AND we see each other away from the DC!!
I did a favour for another friend who I've never helped out before, and she gave me a gift to say thank you which although very kind and thoughtful of her, actually made me feel as though it was a bigger deal than it needed to be.