Let's talk about suffering from love. In general, the expression "suffer from love" sounds rather absurd,
because love is not exactly something that you can suffer from, and indeed you need to figure out what love is. People often pass off their physiological attraction to a person of the opposite sex as love. Thus, endowing purely physiological processes with a romantic meaning.
When these physiological processes change in his partner in the direction of interest in other partners, the "loving" thinks that he has been "out of love". But how can one talk about any romantic crap if the primary motive of the relationship itself is purely biological? A person is inclined to come up with a moral explanation for such relationships, although he himself is guided by the same animal motives, he simply comes up with moral reasons to justify his animal motives.