Our sons are the same age and play together quite well but roughly, lots of tickling and rolling around and chasing. Her son doesn't listen when mine wants to stop so tears ensue sometimes.
At her house recently her son was hitting mine as we ate lunch, and later he shoved my baby repeatedly. Both times she was there but just pretty much ignored it so I told him off.
I really like her but I feel uncomfortable that it falls to me to deal with this. I also hate confrontation and have convinced myself that she's secretly pissed off with me and is going to want to have it out with me.
I hate the diplomacy side of this having children thing!