A few times I’ve went alone too but I’ve hooked up with local cycle tours it just takes some of the stress out of it and you usually find a lot of like minded people and a few in the same boat (alone). A lot of destinations also have a local expat cycling groups. The only thing you can’t be guaranteed that everyone goes your pace.
My last solo trip was with Love Velo in Tenerife (it turns out they were using local guides).
I’ve been to Mallorca a few times for training camps with Mallorca Cycle Tours. (I think those solo trips have been my best experiences, mainly due to larger groups).
And years ago I went with CycleCostaBlanca in Denia (combined with Vuelta stages).
My last trip abroad I did join however, my old Scottish club in Calpe and we had a blast!