Her relationship is posted all over Facebook?

Why do people insist on putting their relationship on public display over Facebook? I know someone who constantly posts photos of everything she does with her partner (even if it's having dinner at McDonald's)... A majority of her status updates are to do with her partner and how wonderful he is, and then she'll post how much she loves him on his wall (for everyone to see). Call me old fashioned, but I'd think she's over-compensating for something? Any theories?