It depends. Is he blowing me off on purpose because he just hates the day? Or doesn't want to be with me? Then yeah, I'd be upset.
If he had a good reason, say work or family/friend thing, then that's fine. I don't want gifts or anything fancy, just to spend time with my guy, so if it can't be on VDay, then we can spend time together another day.
She should take that as a legitimate indicator to break off the relationship unless he was off to war or in the hospital haha, why wouldn't he make the time? what priorities are really that much higher?
You don't have to do anything specifically on Valentine's Day you can schedule to do something together early or late plus on Valentine's Day everywhere is crowded and its best to schedule for another day