Even though they will be bloody disappointed?
He has form for promising treats (swimming, roller skating, cinema) and then not bothering or fobbing them off with another treat in the make believe future.
DC have gone to school excited that daddy is picking up from school and taking them swimming tonight (he has them tues evenings)
He hasn't text to say he's picking them up and he hasn't asked for their swming stuff. Swimming was promised in lieu of another treat which didn't happen at the weekend.
I could phone him and berate him enough that he might take them or I could leave it and let him tell them he forgot or is too busy (and then probably promise another day next week)