A healthy relationship with your ex-partner is generally viewed as an indication of maturity, an outward sign to the world that you're both adult enough to respect what has gone on between you and remain friends.
Your new girlfriend might hate her coming over for dinner, especially if she can't eat refined carbohydrates, but you feel confident and Bond-like in your mixing of former and present lovers.
But new research from the University of Oakland suggests that in fact you're probably a psychopath if you feel the urge to keep an ex partner in your life. Brilliant.
Researchers investigating Post-Relationship-Friendships (PRFs) asked 861 people about their relationship with their ex and their reasons for remaining friends now.
Most people in the research group cited the fact their former partner was reliable or trustworthy as a reason for staying friends. Sounds normal so far, but for men sexual access was rated as a more important factor than for women which despite not being uplifting news isn't all that surprising.
Most interesting though, the participants that scored highly for dark personality traits - for example narcissism, Machiavellianism and psychopathy - were more likely to remain friends with exes and chose strategic reasons such as sexual access rather than emotional ones.
Authors of the study Justin Mogilski and Dr Lisa Welling wrote that:
"Although a break-up nominally marks the end of a romantic relationship, the current research suggests that resource exchange between ex-partners can extend beyond relationship dissolution."
Psychology Today has even weighed in on the complex nature of friending ex-partners, discouraging people from doing so:
Even more proof that you shouldn't be hanging around with your ex. At least your girlfriend will be happy.