So, I'm not sure if my suggestions will be useful depending on how you are implementing COVID practices, but I'll put some stuff out there!
First thing that comes to mind: Is getting an AirBnB in your city an option? My partner and I have done this for a few special occasions since COVID began, along with getting takeout from a fancier restaurant. It's been a nice way to feel like we're getting away and doing something outside our routine, and has definitely felt ~romantic~.
Some other ideas off the top of my head:
-If getting an AirBnB isn't an option, maybe plan an at-home date night? Dress up, light some candles, and order fancy takeout or cook a meal together.
-Make a sexy to-do list of some new things you'd like to try with your partner and pick nights to try them.
-Maybe since the sweatpants don't feel sexy, try to wear "normal" clothes, do makeup (if that's your thing), etc. at least a few times a week, just to ~feel yourself~ a little.
If I think on it a bit, I may come up with a few other ideas, too! Good luck!