We do both get jealous. It happens. But the point of polyamory isn't for your partner to find someone better than you and then leave you for them.
Growing up I didn't know anyone who was non-monogamous. I didn't know what polyamory was, or even the term"non-monogamy." But at the age of 14, I started dating an 18-year-old. I was very young so we weren't in a physical relationship, but I eventually discovered that he was cheating on me and sleeping with someone else who was also older.
Daniel and I started exploring non-monogamy together in 2015, but it happened very slowly. For example, we agreed that if I met someone on a girl's trip to Vegas, I was allowed to do what I wanted. And I did kiss someone. That was as far as I wanted to go. It was fun telling Daniel about it and it didn't hurt our relationship. After that, little things would occur.
Most people think Daniel and I are having lots of sex with other people, which is funny because we are both very slow moving when it comes to that. You could call it; above all we're both attracted to people's personality, intelligence and the way they care about others. I also feel like if I was really attracted to a person, loved their personality and all their great qualities, I don't think it would matter what sex they were. I guess I would identify as pansexual.
But neither of us has ever been in another relationship where the other person didn't know that we are polyamorous, that we live together, have a dog and share expenses. But it's not always going to work out that we both have other partners and can both share half our time with each other and half with them. When I was in the two-year relationship, Daniel wasn't with anyone else for most of that time. Then, more recently Daniel started seeing someone while I wasn't seeing anyone.