I too find myself in the same conundrum. People and contacts just disappear if I don't put effort in it. It is always me who have to follow up for some reason. How did you get over this?
Well, to be honest I didn't. I just started dedicating my time and efforts only for a few select people that are worth it. Otherwise social interaction can be too tiring and even lead to depression. Empty conversations, not loneliness, are what I hate the most.