For most of the time we used couch cushions, pillows, and heavy blankets to simulate room treatments. It was pretty effective and free. Then as time went on he replaced them with ASC bass traps... found some used ones and panels.
This will not look good. But just try it. Pile up couch cushions directly behind the speakers and add heavy blankets on the floor in front of the speakers. If you can also have some pillows at side wall reflections (just at ear level). If you can cover all the windows behind with heavy something... should make a big difference.
Make sure your wife doesn’t see it. Put it away before she gets home... just the sight will drive most women crazy.
But this kind of stuff should give you a little taste of what treatment can do. Good looking ones can be had later.