I'm single, adult child living a distance away, friends and and family all at least an hour away.
Summer's fine as I'm busy with lots of things.
I've started volunteering as music festival steward with Oxfam, which is one reason I'm busy in the summer, would recommend it as it makes it free to attend and loads of people go solo. Makes life a bit more exciting too - I did my first ever Glastonbury this year.
I've found a good local meetup group that has a couple of events most weeks. Find one or start one?
Otherwise in winter I have to be careful not to hibernate/isolate too much. I try to have something 'biggish' at least once a month, usually staying sat night with family or friends, or a day trip to local city with theatre or something. You really need something to look forward to.
Otherwise winter box set binges, lazy weekend morning in bed with croissants and a book, getting out for a walk, video calls with people I can't visit, it does drag on though by Springtime.
I'm thinking of a winter sun holiday this year.