You don't know his circumstances. The agony of being in love and not knowing if the relationship is going to survive a certain impasse can be so intense as to make a person hastily bring it to end, just to get some certainty. They don't do it because they want it to end, but because they just couldn't endure a protracted break down of the relationship. You might say "well they were stupid, they could have saved it if they worked hard" but the thing is in retrospect they agree, it can be a hasty, ill judged decision brought on by the unholy mythic powers of love and they go on to regret it.