I agree with the sentiment of your article but not necessarily the logic. Harvard university (amongst others) have shown that true friendship (though rare) is the most objective indicator of happiness. To me the question is not whether you stay friends with ex-lovers but whether true friendship was a criteria for your choice of lover in the first place. Staying friends with ex work colleagues is similarly rare but the real question is whether you were genuine friends in the first place. I’ve worked and done business with many people and only a fraction are genuine friends today. The same applies to people I went to school and university with. I’ve dated and married more than my fare share and I’m true friends with only a fraction. However if I look back, I never actually lost any of these genuine friendships just because of a relationship status or title change.