Gurl, he has a sister who is VERY YOUNG, if you were to have more sense of responsibility, you would think he will always prioritize his baby sister even more than his own life. If you felt that you're too unimportant for him, then just break up wtf, why cheat? Like I get you're hurt for not being his first priority, but gurl YOU AIN'T EVEN MARRIED YET, and he has a life unlike you who probably have loving parents who look after you and your siblings, parents who provide for you and a family who will love you unconditionally. And clearly all he has is his little sister that you felt insecure to