Rent an apartment, you can afford it.

It turns out that paying monthly rent on an apartment is cheaper than going to a motel. Sure, you have to clean the place yourself, but you could still always hire a maid to come in once a fortnight. And there is no hassle with dealing with motel staff. The two of you can easily have your own keys, or you could install a lock with the key code for quick access. You head to a real estate agent and find a perfect apartment in a quiet area about halfway in between your homes, and sign the lease immediately. It's a relatively small apartment block, meaning there aren't going to be too many residents around. The building is fairly new and appears to be very well sound-proofed compared to older dwellings. And it's located on a quiet street. It seems to tick almost every box.

Gemma asks you if she could live there, and you don't see why not. You're already paying for the rent, and it's not as if anyone else would be using it during the times you're not there. And having her already living there means that you can swing by without having to arrange to meet her there first. Of course, you had planned simply to furnish the apartment with the bare basics, like a mattress and nothing else, but it wouldn't cost too much to deck the place out with some relatively inexpensive furniture. You give her a few thousand dollars to go shopping, and surprisingly through a combination of sales and thrift store purchases, she furnishes the apartment remarkably well. She could have a future in interior design if being your personal whore doesn't work out.