How exactly am I [22F] supposed to consider what my boyfriend [24M] said to me?

This is so silly and weird but I feel like I could use some advice or at least someone else's thoughts on the matter.

My boyfriend of three years and I were just informed last-minute about going to a Halloween costume party tonight. We don't really have the time or the money to go out and buy costumes from a Halloween store, so I had to do some quick thinking on what I already owned that I could possibly turn into a costume.

Well, I finally got the idea to go as Mrs. Robinson from The Graduate, since I have a black silk bathrobe, some black pantyhose and heels, it wouldn't be too hard to style my hair like hers, etc. I told my boyfriend about it when I got the idea, and this is pretty much how the conversation went:

Me: So, I got the idea to go as Mrs. Robinson to the thing tonight. I could wear my bathrobe, some pantyhose, (etc.)

Him: Oh, no, don't do that. I mean, do whatever you want, but I would appreciate it if you didn't go along with that idea.

Me: What? Why not? Don't you think I'd look good?

Him: Of course I do, but I just think it would be weird.

Me: Weird how?

Him: I just mean that I would be embarrassed.

Me: What? Why would you be embarrassed?

Him: I don't want to have a conversation with you about this.

I dropped it after that, but I really am confused. I know that he doesn't have a problem with "sexy" costumes because we've been to several costume parties in the past where I've dressed a bit more provocatively and he was fine with it and even liked it a lot. How would you say I'm supposed to take this? I really have no answers.

TL;DR: My boyfriend says that my costume idea would embarrass him and when I asked him why he just shut me down. He hasn't ever had a problem with any of my other costumes in the past and I don't know what he means by his weird objections.

Submitted October 26, 2019 at 10:26AM by bloopsnooter https://ift.tt/2okCN1I