Nah it's definitely both but your statement is still accurate. People can know they are into something but if they have some issues in the relationship that they haven't worked on, or have some confidence issues, proper rules haven't been established, etc, they can find out real quick that things can go bad.
I have seen and heard about too many stories of this. Guys that force their girl to look for other girls as if they want to have a solo relationship and then bring up a 3some. Or guys being overbearing and making all of the decisions for the woman who just goes along with whatever. Or either partner just not being ready to see the other partner being pleased by someone else. Hell they even did that on an episode of The Game when the main character tried to give her man a woman for a 3some.
Just how there are tons of fetishes and dub categories for sex and lifestyles, there are tons of factors that can cause issues.
I hear you, I think maybe the relationship\love has to be strong between the two. Meaning that no matter what it’ll be them two in the end.
But I don’t necessarily believe that the people are strong or stronger who do participate in that lifestyle than those that don’t participate in the lifestyle.
If that makes sense.