What event caused irreparable damage to Althea and Oliver's friendship in the novel, Althea & Oliver?

When Althea rapes Oliver, it is the turning point of their relationship. Althea is wounded that they had sex and Oliver had no recollection of it and Oliver is outraged that Althea took advantage of him during a sleeping episode. If they were ever going to have sex, Oliver wanted to be fully present, and as it occurred he was still in a sleep state even though his body was responsive. This is the point of no return for both of them, and their relationship will never be the same.