Before I go any further, I just want to clarify again that if you believe he has a problem with alcohol, I absolutely agree with the advice to talk with him about it, and start pursuing a plan to reduce his consumption in general.

That said, again, if that's not the case...

Every once in awhile—like, maybe one in every five or six weekends or so—I start feeling done for the night sooner than Tim does.

So, again, just to clarify - the nights you're fine staying out, you both stay out, but the nights you want to go home before him, you both go home? That still does sound like your feelings are overriding his here.

But on some nights when we’re out together, I feel myself getting tired but would still ideally like us to go home together so that we can have sex, sleep together in the same bed, etc.

Per your other quote, this happens less than once a month. Is it really such a big deal to not go home and have sex together, that one night every 5-6 weekends?

If there are broader problems with a lack of intimacy or sexual incompatibilities, those should certainly be addressed.

But if this is as infrequent as you say, then I'm struggling to understand why you can't just go home alone that one night? Also, wouldn't this aspect of it still be an issue if he stayed out with friends? How does it change if he's staying out alone instead?

It kind of seems like your (legitimate) worries about his alcohol intake, and your personal desire to have him go home with you on your time preferences, are getting a bit conflated here.