Why wouldn't you?

[She raises an eyebrow in challenge. Seems a strange sort of assumption to make, Sirius.]

And we're dating, not married. [Dating very seriously, yes, and she had it in mind to ask him to meet her parents over the coming holidays, but-- married? Hardly.] Even if that were the case, it's not as though you don't have time, if that's the sort of thing you want for yourself.