Most Helpful Girl
In a monogamous relationship? No
In an Open, sexually fluid relationship? Yes, possibly, depending on the standards/agreement in the relationship.
There are people in open relationships that find emotional cheating unacceptable and breakup worthy. There are people in open relationships that find physical cheating behind their backs unacceptable and breakup worthy.
It depends on the relationship and what two people agree on. IT also depends on the boundaries in the relationship, and how much someone is willing to deal with. If you don't forgive/date cheaters then its not something that you should have to deal with.