People need to get involved in their communities and make local friends, which it sounds like they have done if they're always going out.
Technology based friendships have never appealed to me, could never see the point. That sort of thing is what keeps friendships going in between meeting up, IMO. If you're now all sufficiently old that meeting up isn't realistic any more then I can see why they've let the friendship go a bit and might fade out completely over time or just reduce to Christmas cards maybe.
Every friend I've had (both sexes) says when they got to around 50 they felt they wanted to slow down. I think it hits women particularly hard if they're experiencing menopause symptoms too, especially if they're still trying to work full time and/or have elderly parents or teenage children to deal with.
Most female work colleagues I had when younger, their DC had moved out by the time the parents were in their 50s, but even so they couldn't wait to retire at 60, they felt old and creaky and needed a rest from the daily grind, they were counting down the years and many ended up going part time throughout their 50s because they just couldn't take It all any more.
Now people work until 68, they haven't even got the countdown of the last ten years to go, which would make a huge difference psychologically, being able to tell yourself "just a few more years". Added to that anyone renting or unable to buy a house when they were younger, will have huge payments each month so probably can't afford to go part time for upto 18yrs from 50, despite how they may be feeling health-wise.
It sounds like a long distance friendship where you're possibly never going to see each other again just isn't a priority for them any more. Doesn't mean they don't care about you, just that it's not practical to maintain the friendship to any great degree any more.