nah, I've been just kinda spamming days trying to get it to pop, with no luck. I think it's the only way I'd likely get it is on purpose.

(Oh and if you mean sleep with her in the wholesome sense, then yes. Just no sex.)

update, so I got it to trigger, and I think you're right. ~5 days after you unlock the ability to sleep with her (this is weird to say in a game where you can have sex with her on a regular basis, even before you know her at all) I got it to pop, and then could get it again 5-7 days after, as to the longer wait before. So I do think that unlock is a pre-requisite.