Im an old hand at this, for various reasons dont want to depress anybody and i've developed a few skills around it..
To start with, I avoid situations that rub my nose in it. I can honestly say I've never noticed what others are buying in the supermarket but, If I did, I'd avoid it. I just can't see the point of doing something that makes me feel shit. I don't socialise too much with marrieds, rich people, people whose children are doing well. Etc! I just don't want it in my face.
It doesn't make my life smaller, it's more a case of self-care really. I spend time with/do things with people in the same/similar boat.
Good idea to get out to something first thing on a weekend, it always gives me a boost to do that, I feel I'm in the land of the living!
I know it's not easy but I really do look to accept the situation I'm in. Not passively but I'm a legit human being, whether or not I have the frills some people seem to have. A lot of loneliness and isolation is down to the way society is structured and not personal at all.
I have a friend who does friend/boyf homework, she's on it! I keep my eye on that, too; keeping my toe in, making sure I factor in socials/meet-ups [sorry about the endless obliques here ha/ha].
Ime friends come and go, I hold friendships lightly these days. I'm quite boundaried around friendships though - if someone takes the piss I back right off (and people really do take the piss I find!). And I want to spend time with people who want to spend time with me, otherwise I am simply not interested (why would I be??)
I'd MUCH rather spend time alone than with people for the sake of it. I am an extrovert but everyone finds new situations difficult, you just have to be brave and get over that initial hump. Though if it's not going well I leave. Try something else...
Thus pronounceth I on loneliness/isolation! I'm not ashamed of it is the bottom line and that's half the battle imo.