Complex sentence: Not long after the confrontation Kirk's cousin Jack takes an interest in his cousins affair and decides to interfere, and against Kirk's wishes, he goes to see Tira to ask her to leave Kirk and his fiancé alone.
Split into simpler sentences: Not long after the confrontation Kirk's cousin Jack takes an interest in his cousin's affair and decides to interfere. Against Kirk's wishes, he goes to see Tira to ask her to leave Kirk and his fiancé alone.