Complex sentence: At the end of season 8, she and Leonard were heading to Vegas to get married only for her to find out, on the way there, that Leonard was unfaithful on a work related boat trip.
Split into simpler sentences: At the end of season 8, she and Leonard were heading to Vegas to get married. Only for her to find out, on the way there, that Leonard was unfaithful on a work related boat trip.