Well we didn't know what happend in their relationship in the last 5 yrs. Might happpend JJ is already tired because of Leo's shits. You know sometimes you'll get tired with your partner especially when you keep on telling him/her what is the problem and as time passes by he/she is not willing to sort out that. You'll just do silent treatment hoping he/she realize it until you get tired and decided just to break up.