Largely alone nowadays as being a car-free utility cyclist doesn't lend itself to beiing social. And if I do a purely fitness ride it's always solo.
There is a good friend with whom I would ride quite frequently years past. We would do 80-100 mile fixed gear rides at night on the Natchez Trace Parkway in TN. I lived .5 mi. from the Trace by mile post 423 and once in awhile we'd ride south to the Alabama border and back. Never at night though. Not enough battery time for our lights. One night we DID ride w/o lighting as the moon was SO bright we didn't need any. Except for rear blinkies of course.
In the spring and fall we had a couple other fixed gear riders with whom we'd ride a city course on Nashville's MUPs. Going out was a pleasure as we'd start very early. Coming back was always a PITA dodging walkers, runners, baby carts, roller bladers, etc. All in a day's outing. lol Then there was the occasional roadie who'd go blasting by that we would inevitably re-pass on climbs. 🙂
For a pretty solid length of time my ex and I rode together frequently. Then she got bored with it and sold her bike. But, it WAS fun while it lasted.
Also, for a number of years I was a 200+ mile per week commuter. For 10 years I did between 8500-12000 miles per. Was riding everywhere. We lived rural so everything needed was at least 15 miles away. Had a trailer/mtb rig I would use for grocery hits. The supermarket was 17 miles away w/a 550 ft vertical drop/climb. More than once I'd go so long w/o driving my truck the battery would go dead. lol Goes without saying that commuting was ALWAYS solo.
Again living car-free doesn't allow for many social cycling forays. If any at all.