Am long term single so I've had this a few times now. I do try to make an effort with my limited social life when I've not got dcs. I'm genuinely pleased for my single friends when they meet someone and I know they have the honeymoon period and I don't expect to see them as much. But I've had two or three do a complete disappearing act, seeing the new man every day, if you try to see them they bring him along too. I tend to not say anything and just let the friendship drift but I do feel sad really.