[...Okay, that was a... weird little hip bump? Possibly kind of flirtatious??? It's hard to tell, but she's never seen that to be a normal casual kind of thing, so Toriel should-]

I have a girlfriend.

[...find a way politely make her disinterest in that known, but instead she just kinda blurted that out weirdly. Great!

Toriel's just going to clear her throat, and just start walking and answer her question and hopefully not leave much time to address that.]

Well, my best guess would probably be one of the tea rooms? There are a great deal of them and I think they are a popular choice for those wishing for a little isolation!