Should I go out for halloween? Is this a good costume?

Well, I can understand where your boyfriend might not be too happy with you dressing up in something y, but if you want to I say go for it. With tights, that outfit won't be as skimpy and it would look really cute. I think if your boyfriend is going to be with you then he should be understanding enough to let you do it without too much of a fuss. And you definitely should go out! If you miss this opportunity, you might regret it later. I think you really do want to go, you're just looking for approval! :)