I can relate very much to your post OP. I also made the decision not to have another relationship in my early 50's after a divorce and long term relationships. Adult sons had left home.
I felt the need for peace and quiet with as little stress as possible. Not particularly sociable, and with a 'rich inner life', I have been able to live life more on my terms with few demands and my own timetable, meeting my own needs.
I'm not a consumer but spend time refurbishing my property, gardening, renovating furniture, reading loads, baking, word puzzles/crosswords, writing, cinema, walking...simple pleasures, and have never been happier.
Years after my decision and I feel content. I see my family every few weeks, a special friend every weekend when we have good times, days/events/meals out...and another friend about 5-6 times a year.
It works for me. Life has been hectic, stressful in many ways in the past, but I've had a lot of great experiences and a lot of good times and fun. It's just different now. I wish to observe life, think and appreciate how lucky I have been in many ways [unlucky in others!]
I love nature, greenery, woods, fields, beaches, cliffs, dunes, birdsong, trees, plants, flowers...the concrete, commercial, competitive, plastic, rat race world does not appeal.