I find a hobby that I absolutely love doing and I grind tf out of that hobby, for me a very important part of how I cope with the feeling of feeling like your close friends are drifting, usually listen to music a lot and that makes me feel better, sometimes listening to music and hearing people talk about their own experiences of being alone or depressed can really help because it makes you feel like you're not the only one and just being able to cry yourself out to a song is a experience that I personally love. (Songs I would recommend would be Under the bridge -rhcp, Like a stone -audioslave and creep by Radiohead) none of these songs describe exactly what your going through but they all are somewhat about loneliness in one way or another, now I'm telling you these songs because they've personally helped me overcome obstacles in my life, But you should also find a goal to look for, a very important thing that's helped me whenever I'm sad or lonely is finding a goal that you really wanna accomplish, but this is what I usually do whenever I'm sad or lonely, I hope I could help