Okay how he worded it sounds really bad but its natural to lose attraction to someone its biology! everyone is a bit shallow because of our natural make up and instincts, we arent so different from animals who do certain things to attract a mate. This happens all the time and yeah both parties will be sad if a break up happens but thats what separates us from animals, we can feel guilt and that is probably why he is asking, because he realizes something is different and he feels different.