Booked a 3D scan for today as thought this would be a lovely thing to do as a family (dh, ds and 2 dss) at Christmas and told older step children about it a few weeks ago. One showed no interest and said at the time he would probably have plans so I let it go there and then but other ( who lives with us full time ) said yes,great, he'd be there. This morning he has clearly forgotten and announces he has a guest coming round, I was not consulted directly but pointed out to dh that guest should be put off until later in the day as a previous commitment has been made but dh decides to take the easy route and just let it go. Left feeling really crushed, dh can't see why I am upset and can't understand that he should be showing his adult sons that if you have committed to something you should see it through, even if you have forgotten once reminded you should stick with first commitment. Note my parents would have loved to have come but I didn't invite as was treating it as a thing for just the 5 of us. AIBU?