i think so. a bachelor party and subsequent wedding hopefully only occur once in a person's life. he can celebrate your birthday on another day. he can't celibrate a person's bachelor party on another day
That is actually a very tricky thing for the both of you. Is the friend like REALLY close to him? If yes, then it explains his decision a little.
He could have also made time for the both of you, like divide his day. If he didn't maybe he will make it up to you later if he absolutely couldn't ditch his friend's bachelor's. ALSO, he may not be all that into celebrating birthdays.
If we haven't been dating long, I wouldn't worry about it. Even if we had been dating long, I wouldn't want to keep him from his friends. We can celebrate my birthday earlier in the day, or another day perhaps.
That's kinda fucked up. At the very least if it was so important for him to go, he should have tried to reschedule your celebration first. If he couldn't, then sorry, but the bachelor party should have been dropped, not you.
He shouldn't go to the bachelor party. But I'm also not surprised he is. He should stay home with you for your birthday, he should want nothing more than to spend it with you. He is probably just not a sentimental or sensitive guy. And if that is your type then don't spend any more time with this one, and you deserve to be happy.