BIRTHDAY ADVICE

ok so for the past month i have been planning a big event for my birthday coming up which is a big birthday for me. i didn’t have an exact date or time but had narrowed it down to the week and my boyfriend was aware of that. today he asks what day my party is and i tell him and he says “oh ___ asked me to go snowboarding that week because he rented a super nice cabin” he then proceeds to ask me if he should go or if I would be mad. Of course I wouldn’t be happy I’ve been looking forward to this day for a while and really want him to be there. But I also don’t want him to just come because he feels guilty. I want him to be there because he WANTS to. and obviously im sure he’d rather go snowboarding which hurts... he’s a big boy he can make his own decisions but i really don’t know how to feel or if I’m overreacting. Would you be okay with your boyfriend missing your birthday to go do something else or would be a little angry.