Originally Posted by sevechten
... there's no guarantee that she can handle an open relationship at all--and our agreement was to try it, not that once she said yes we could never go back to a mono relationship.
I understand that, but think about the people you would be "trying it" with - people who are real flesh-and-blood human beings with desires, wants, needs, and whose feelings can be hurt. They are not there to be experimented on. Since you said you didn't want to "settle" for "very casual outside relationships with little emotional connection," I think you get what I'm trying to say, and why a veto, for many people, would be at odds with developing real, loving, caring relationships.
I would also add that, although it is perfectly reasonable to leave the door open as to whether polyamory is for you, and to be able to choose monogamy in your life again if you want to (which is what I do myself), it is still important (IMHO) if an when you do get involved with an additional partner, that you go "all in." I mean, it's like any other relationship when it just starts out, there's a giddiness and a hesitancy at first, an "is this really happening?" feeling, but then you go deeper and you invest in it fully, because to hold back would be unfair to the other person (and to yourself). Of course, there are no guarantees that any relationship will last, whether poly or mono, and I'm projecting into the future a bit (you're not even sure if there is chemistry between you and P. yet!) but as long as you are willing to dive in fully and wholeheartedly, I think you will both give and get the best in "loving more than one."