Forgive me, I’ve tried polyamory but I don’t quite know what counts as “cheating” when the relationship is opened like this.
So my sister (14) “Liz” went out with “Asher” (16) for like a week. Asher was always very giggly, flirty, and romantic with Liz and would find couple songs and say “That’s us!”. My sister seemed very happy with her new boyfriend.
Asher turned out to have a boyfriend he had been dating for a year before Liz. Liz knew about the boyfriend, but since he said “I’m poly and in an open relationship”, we all assumed the boyfriend was okay with it.
Turns out, he wasn’t okay with it and Asher got into a relationship with Liz before telling “BF”. Then, afterwards, he said “Well I like “BF” first and I like him better than you so I’m breaking up with you.”
Maybe I’m too upset because she’s my sister, but kind of a jerk move there on his end.
So, one possibility is that Asher is a jerk, and never actually was in an open relationship with his bf, or else he and his bf were in an open relationship, but had a boundary that they had to ask the others’ permission before hooking up with other partners (or something similar).
The other possibility is that Asher and his bf had agreed to an open relationship, but had never really discussed the details, and both a had different ideas about what was and wasn’t acceptable.
And yet another possibility is that they had an open relationship, and they’d agreed that what Asher did was totally acceptable - but that when faced with the actual reality come to life, Asher’s bf was not okay with it.
This is why there has been a metric ton of ink spilled in nonmonogamous spaces about - say it with me - good communication. But of course, these are teens. And they likely haven’t had much experience being nonmonogamous. So I’d just chalk this up as being a learning experience for everyone.
Imo, what your sister should take away is that you shouldn’t get too invested in a non-monogamous person without meeting their partners (or at least their friends who are involved in their nonmonogamous circles). Sure, flirt and fool around and have fun - but don’t assume it is anything beyond that until you have actually interacted with the other important people in their lives.
As someone who is nonmonogamous, personally I think everyone should try having an open relationship at some point in their lives. Not because everyone should be nonmonogamous. But because it’s going to dredge up a whole lot of emotional baggage and force you to deal with it, while also making you extremely good at communicating with your partner(s). Having multiple partners is awesome - it is, no doubt, really fucking hot. But at the same time, it is basically like having a second job in terms of work. So anyone going in should be aware of that caveat.