I just wonder if it's helpful to consider ex's and friends in the same way. In my experience, it's not worth fantasising over ex's that might come back - you split for a reason, after all. Friends are a different matter and there's some sound advice above about that. But frankly, a bit of loneliness can be useful, for me at least. It makes me more inclined to go to my groups and take part in community activities, rather than just hook up with friends and get drunk in bars.