What is the evolutionary reason guys take longer to get over a breakup/divorce than girls and don't recover completely?

It's because women tend to have closer friend and support systems than do men and women are more likely to be able to talk about their feelings, thus gaining control over them. Men tend to go silent and try to weather a breakup internally and sometimes through self destructive habits, like binge drinking. Women just communicate better than that's almost certainly why they can get through rough times better than men. 

Most divorces are initiated by women on their terms and their time frames.  Many women already have another guy in mind when they decide to call it quits with the initial guy.  

Just a theory. It might be built into our dna. When one tribe conquers another, the males of losing tribe are killed and the females are kept alive for breeding. Females may have evolved the ability to quickly let go and accept the new males.

back in the day, women did as they were told by men. Men ruled! women were submissive and fearful of men. now, women have rights and legal recourse, so men have to behave themselves. Besides girls know guys only want one thing. when men can't have it, they either get aggressive or pout. men tend to be extremists and have very limited emotional range. women have always run the entire gamut of emotions.