A new research into the psychology of social media behaviour shows why couples who share more online are less happy,.
A study last year, based on a survey of 800 men, found that narcissism and psychopathy predicted the number of selfies people posted on social networking sites, and how much the images were edited.
Posting, tagging and commenting on photos on Facebook are associated with narcissism for both men and women, according to a study of 410 participants.
For women, status updates were also linked to these traits.
Happy individuals make for happier couples, and happier individuals use Facebook less often, according to research.
One study in Denmark found that participants who went without Facebook for a week reported being significantly happier than the control group, who carried on using it as normal.
Another study found that spending more time on Facebook was linked to worse psychological health.
Researchers found this was because people spent more time negatively comparing themselves to others.
One study found that couples who post often about their relationships are more likely to be feeling insecure.
Researchers from Northwestern University surveyed more than 100 couples, and found that people posted more on social media about their partner when they were feeling insecure in their relationship.
Research from Albright College found that people who had what’s called 'relationship contingent self-esteem' (an unhealthy form of self-esteem that depends on how well your relationship is going) post mushy and smug updates on social media.