Later it is discovered that Austin was having an affair with Summer's aunt Abby, leaving Summer heartbroken and confused as she is grieving for her husband and mad that he cheated on her. Kyle also has come back to town and revealed that he first came back to confront Austin about his affair with Abby leaving Summer angry that Kyle didn't first tell her. However, Summer forgives Kyle and he continues comforting her over her loss. Then the person who killed Austin begins threatening Summer, Kyle, Noah, Courtney, and Abby. As time goes by, they keep looking for the killer which causes the killer to strike again - this time killing Courtney on her wedding day before she was to marry Noah. This leaves Summer heartbroken as she has now lost her husband and best friend, and so Kyle remains by her side to help her in her grieving. Summer suspects Sharon as the killer, which causes a rift between her and Noah. Later, Summer attends a party with Kyle to get her mind off of everything. After the party at her house, Summer talks about Courtney then tells Kyle that she can't keep dragging Kyle into her misery but Kyle says that that's what he is here for and that they were family for a little while at least but Summer says she doesn't look at him and see a brother and Kyle says he's not and he never was. Summer looks at Kyle and says no you weren't. Kyle and Summer look deeply at each other and then kiss, which leads to them making love for the first time. Afterwards Summer tells Kyle that it feels so good to be with him. They both also say it feels so natural being with each other even after they were told that it was unnatural. Summer says that it was unfair that they were kept apart because of Sharon's lie. Then Noah sees them and gets mad because Kyle took advantage of Summer. After Noah leaves Kyle tells Summer not to feel ashamed, that what they did isn't wrong and that Noah is just grieving. Later Summer and Noah make up and he apologizes. Sharon is arrested soon after as evidence points to her. Noah defends her but Summer continues to believe she is guilty.