If your point is that going on about evolutionary psychology adds to the obfuscation but not to the insensitivity, I disagree. There are often ways of more or less sensitively coming clean about (what one takes to be) one’s true reasons for breaking up. Maybe you wouldn’t go so specific as “you’re too fat,” but you could talk about lack of physical chemistry or whatever without uttering a falsehood or being too misunderstood. But there is no way of sensitively taking your devastated ex aside and handing him/her a Tooby and Cosmides paper to read for homework.
If your point is that going on about evolutionary psychology adds to the obfuscation but not to the insensitivity, I disagree. There are often ways of more or less sensitively coming clean about (what one takes to be) one’s true reasons for breaking up. Maybe you wouldn’t go so specific as “you’re too fat,” but you could talk about lack of physical chemistry or whatever without uttering a falsehood or being too misunderstood. But there is no way of sensitively taking your devastated ex aside and handing him/her a Tooby and Cosmides paper to read for homework.