I know how you feel …not with mountian biking but with rock climbing.
I use to go rock climbing 2 to 3 times a week but I’ve just fell out of love. I lost the strength and fitness required and just lost ability. Climbing lower grades and working my way back to where I was just seemed like too much hard work.
With mountain biking I feel fit, fast and good. That helps a lot, (It helps that I can ride stright out of my door tbh, although I could also walk to a crag!)
I’ve thought about selling up and moving on but I still have ambitions to climb big stuff in the alps and beyond.
So I’ve moved into ski mountaineering and this winter (i.e. now) I’m going indoors to train and start rebuilding my strength. I’ve not done it yet though ….night riding is whey too much fun!
All I can suggest is try riding in the evenings locally or short afternoon blasts. Make it social and the love will soon come back.