Its called being a mom... When we "host" a party we never see the focus of it. Birthdays or any party... The kids are playing, the other parents are talking and mingling, we are serving, planning, smoothing, arranging, restocking, cooking, refreshing, cleaning, picking up or putting down, etc.
There is no reason to feel bad about it. If it is something you don't want to repeat, then next time make a very focused list for hubby to do for a while and tell him its YOUR turn. :-)
Life and parenting is a process of trial and error. Live and learn.
I really doubt if your child is thinking you don't love him cause you didn't play with him. Sit and look at the pictures and ask him about what HE liked about it. Let him tell you about it.