Am I wrong for not wanting to try it?

Lately my boyfriend has been into the idea of butt stuff. He's been touching me close to my butt & stuff like that. I told him my hard boundary is anything close to the opening, and he constantly says "for now." I'm open to things close to it but I'm uncomfy with anything near my butt. He'll get too close and I'll say that's a no, and he still says "for now." And also, he's persistent about "me thinking I'm not into it, but i secretly am/will be." I told him I'm not interested and I don't know if I'll be into it in the future and he always says the same thing- "you will be."

He also continues to touch me near there and tells me what he "knows" I like. For example, he'll lightly/quickly graze over the opening and tell me i secretly liked it. I don't and he doesn't understand that.

Should I be more open to it? What should I say? I don't think I'm ever going to be into it but he's persistent.