Xposted ETA/Update: Fiance did end up canceling his plans to avoid conflict, but he still doesn't necessarily understand my feelings or think they are valid. He thinks because he canceled the plans I should just let it go and drop it. He doesn't understand why I'm still upset that he had these expectations in the first place.

Fiance 33M has 2 kids from a past relationship 6M & 8M, and Fiance works weekends. Since the children's mother has primary custody and lives 45 minutes away, I watch them on weekend days while fiance is at work so that he can have time to see and spend time with them at night when he gets home from work.

Fiance made plans for Sunday (tomorrow) night and asked me about the plans as he was making them. I asked what about the boys and he said they could come with us and if they got too cold (plans were outdoor) we are only 20 minutes away.

I assumed this meant if the boys wanted to leave we would all leave. Apparently, as it turns out fiance assumed that I would take the boys home with me while he enjoyed the rest of the evening with his friends. I'm very upset by this. I watch the boys so that fiance can spend time with them when the opportunity is there, not to give their mother a break or because I'm their parent or even obligated to do so. When I started to get upset, fiance offered alternatives such as his mother watching them while we went. I dont think he understands the point that I sacrifice my entire weekend so that he can spend 3 nights (about 4-5 hours each night between when fiance gets home and bedtime). If he is choosing to put the boys with a sitter (any sitter, even if its not me) to do something else during the time he could be spending time with them, I feel like him spending time with them is worth way more to me than it is to him. I told fiance that I feel less like I am doing this for his benefit and more like I am just free childcare so he can say he takes the boys every weekend. Fiance thinks the whole thjng is a misunderstanding and that ive wasted a day trying to force a "ridiculous conversation". He thinks I'm being too sensitive about the situation and refuses to validate my feelings on it in any way. Meanwhile, I've spent the last 5 hours crying in our room because I feel like our whole relationship is just based on convenience.

TLDR; fiance is choosing to spend time with his friends over his children when I watch the children for free all weekend so that he has the option to spend time with them.