Kung hindi talaga pwede imove yung date ng bakasyon with the friends.. maybe you can sit down with him to explain how much you need and have been wanting the vacation?
For me, it's not selfish of you to want to go on that vacation na matagal nang naplano and which you feel that you need. If you're bf would still prefer you in his graduation even after explaining.. think which you prioritize more. but know that if he doesn't want you to go but you still do, it might be a permanent dent in your relationship that he may never forget. Sit down and talk, explain your side. let him explain his. Listen. then maybe you can come up with a solution that is favorable for both of you.