I mean to be fair a lot of polyamorous people who identify as such have a different definition of what it means to be poly than you do.

There are unicorn hunters that call themselves poly.

There are a LOT of poly people who demand that the preexisting relationship stays the top priority and do not want their partners to sleep over with the metamour, make life decisions with the metamour, do things with the metamour outside of what they have agreed ahead of time with their primary partner is OK.

That is putting restrictions on their partner's ability to fall in love as deeply with the metamour as they are with them.

In my experience which I'll admit is not universal, this behaviour in polyamory is more common than not.

This happened to me in my relationship which initially started off poly. My partner was in a polyfidelous relationship with two other women, and they had an agreement that all of them in the relationship would love each other equally, so it wouldn't be a V it would be a triangle. And that if anyone in the relationship wanted to have an experience with someone outside the triad, they would ask for permission and get a "hall pass" where they would go off, explore the feelings as friends with benefits for a while, and then if they wanted the relationship to be long term with this new person that person would need to become part of the triad and become in love with the other two members as well.

Initially I was OK with this as the "new person" because I saw my partner as a dear friend who I wanted to have sex with but didn't feel romantically for. However as time went on I did start to have deeper feelings and fell deeply in love, as he did with me. And I had to tell him, "I can't make myself fall in love with the other people in your relationship! It's not fair to expect me to do something like that to be a part of your life!!" and so the definitions of that relationship changed, the entire triad changed, and while it was communicated as honestly and kindly as we could it still led to hurt feelings on behalf of the existing poly partners. Especially given that one night when me and my partner were on LSD after he had come to spend time with me in Australia, we had a profound spiritual experience that made me realise we were soulmates and overcome with emotion he asked me to marry him and I said yes.

Was that appropriate poly behaviour? No. And we realised that as soon as the trip ended and did our best to try and make it work as ethically as we could. But at the same time it was not something that was planned to happen, it was spontaneous, and it was a risk that was inherent to the poly experience altogether. And once the feelings are out of the bag, you can't put them back in without ruining something precious. If he had said to me "I take it back, forget what I said because I didn't ask my poly partners ahead of time if I could ask you that question" it would have devastated me because what we shared in that experience was so profound and we both still did (and still do) feel the same way almost 5 years on. Likewise when he told his other partners that our love had deepened beyond what he expected it to, but that he still loved them as much as he had before - he was being honest but it still hurt them a lot because they had expected it to stay a friends with benefits thing and so to learn that our feelings had changed was a shock.

And yes in an ideal world (and ideal we tried to honour) was that before changing your feelings for someone and deciding you want them in your life long term you would ask your existing partners first. But what if they said "no"? And how would it make the new partner feel to know that the security of their love hung on the word of two other people who were being treated as more important in the course of your life than you were?

The risk is always there that your partner may fall more deeply in love with someone else than they do with you. Even if they don't intend to. And the likelihood of that happening is much higher when you give someone carte blanche to explore their feelings with multiple people. Because even though my partner did still love his other partners, and wanted them in his life, he did realise that our love was stronger (and years later this is still the case).

That honestly could happen with Flo too you know. I know that you're secure in his love for you, but how would you feel if he discovered that he loved someone else more than you? Still loving you though? It would be hurtful as fuck wouldn't it?

And yet that can happen so easily in polyamory.

I'm not saying polyamory is bad but it's also not as easy and ethical as you portray it as. People usually go into polyamory thinking they will have more control over their feelings than they actually do.