he wasn't mad at the fact that lee dojae is a playboy, he knew that. but when euntak asked him to go on 3 dates with him, he asked him not to see anyone else during that and he did. it's not cheating but if he was gonna break the agreement might as well refused altogether, u cannot call him overreacting, if u go back to their very first date, after lee dojae took euntak home he went and sleep with someone else, i said it before that you might be ok with ur date sleeping with someone else after taking u out but other people might not be ok with it. everyone has limit in everything differently. that's just my opinion