But only insecure people need to show off like that.
Another example that bothered me was an adoptive mother and her adult adopted daughter. The mother made some complimentary remarks to the daughter that I thought were very intimate. She seemed to be saying to the world at large, “Look at what a wonderful relationship I’ve got with my adopted daughter.”
I thought she must be feeling very insecure to be doing that in public on Facebook. Facebook can be set for friends or for private, so that the public cannot see these intimate interactions.
If you do that, I see no problem exchanging messages with your girlfriend on Facebook. But why not use email or text-messaging?