While I have never ridden "professionally" I have always loved a good ride, trails, etc. When I was an adult and able to buy/keep my own I began having my own ride
Life happens, had to sell and try to survive. Yrs later, more riders which I loved again. Then, no time. Placed mare in loving home. Sadly decided my riding days were not sufficient for owning one.
Fast forward many, many years
Own a herd of minis at this time. STILL have the desire to ride but, cannot justify buying for the few hrs a yr I would actually do so. Several friends have their horses who are not being used. I have found that I can help them by riding theirs on occassion!
If you truly feel you cannot give this mare more than she is now receiving, maybe you should continue to ride those of your friend and help them out in doing so! I know, I know it isn't the "same" but I have fought with myself over this several times in looking at a "great for me, needs me" horse. To date I have no biggies and find this is the right decision. One phone call and I could ride today. It isn't the same when you consider the emotional contact but, I have a farm full of minis to provide that.
Just a consideration. Matt, if I were your age and not my own 63, I probably buy that girl