An open relationship was one which allowed for intimate contact with those outside of it. Typically, rules or boundaries set appropriate conduct within such an arrangement.
Tyler Steele was once in a serious open relationship with Damian. Terrified of needing someone, according to Orr, Tyler purposely sabotaged the relationship by "straying", by doing things with others he was not allowed to do. This hurt Damian, and the pair subsequently broke off their relationship. (AUDIO: Orr)