Summarize:

Your boyfriend may have made plans for the prom before you started dating, or he may have no intention of going to the prom. If you want to go together, you need to ask him to make sure you're on the same page. It's a good idea to ask a few months in advance so you can come up with other plans if your boyfriend can't go with you. It may be that your boyfriend is already in the process of planning an elaborate promposal for you, in which case, you wouldn't want to ruin it by asking him first. Before you ask him, consider talking to his friends and/or family to find out if he has something in the works. Certain guys may have a problem with a girl asking a guy, so make sure to think about how he will feel. If you decide that asking your boyfriend to prom is the right decision for you, it's important to keep his individual preferences in mind. If your boyfriend is shy or easily embarrassed, you may not want to go over the top with a public promposal. If he loves attention, then don't be afraid to make it a big spectacle. It's important to keep your boyfriend's interests in mind when deciding how you will ask. Show him that you put a lot of thought into the invitation by incorporating something personal, If your boyfriend loves sports, think of a way to incorporate his favorite sport into your promposal. You could, for example, spell out your message with basketballs or baseball bats. If your boyfriend is a movie buff, consider incorporating a funny quote or picture from his favorite movie into your invitation. If your boyfriend belongs to the robotics club at your school, consider using a toy robot to deliver your invitation.
Don't assume you and your boyfriend are going together. Find out if he's planning something. Think about his preferences. Personalize your invitation.