How do I have sex with girlfriend?
Carefully, I hope?
Beat me to it!
... And on the serious side, I second the question of whether you've got any friends that may be able to help out. Also, I don't know how large a town you live in, but maybe AirBnB could help? Friendly people, rather cheaper than most hotels... If you were straightforward about your intentions to prospective hosts, you might find a sympathetic soul - a single woman with a flat to herself, for instance - who could trust you two to have the run of her place while she goes out and sees a movie or something. Might still cost you a bit, but would probably be a lot cozier/less sketchy-feeling than a cheap motel.
In short, possibilities abound for the enterprising Trekker. Get creative! No guts, no glory.