Complex sentence: Eventually, Leanne agrees to go out with Peter but they only have a few dates when Peter has to return to Portsmouth briefly and while he is away, his drink problems come to a head and he ends up in rehab.
Split into simpler sentences: Eventually, Leanne agrees to go out with him but they only date a few times before Peter has to return to Portsmouth briefly. While he is away, his drink problems come to a head and he ends up in rehab.