I hate it when you work with people and they talk to you everyday on phone, social media,out /in…

I hate it when you work with people and they talk to you everyday on phone, social media,out /in work . and after not working with them for a month more or less they act like they never knew u and ignore u. I mean I have friends and closer to my age I just don't see how people can act like your family and when u don't see them as much they cut you off.