Thanks again for the welcomes and reply (Awesome to see an FSPer here, Porcupine! Congrats on making the move too!)
Hi there, YGirl
I can understand what you're saying and if I was never married and didn't have a 19 year relationship with my wife, then things would be different, but I do have preexisting commitments to my wife that (currently) come before interests outside out marriage.
If someone else were a part of this for some time, then I'm certain it would be more balanced but currently my primary concerns are with regard to my wife with whom I have children as well.
Probably my main concern would be if someone else became a major part of my life, desired a long term relationship as well and I made commitments in that respect also but found later conflict arose between her and my wife (I don't think it's too likely, but still a real concern), then things wouldn't be as easy to resolve, but for now the truth is that yes, my wife could "pull the plug" to an extent, though admittedly it's not purely her decision but she has a large influence in it.
Of course, not all relationships are identical but that's basically the state of things for me currently. If I had always had intentions to have a polyamorous relationship then things would have been different all along (and yes, that's something I've thought about over time).
So there were at least implicit agreements and obligations made when I married my wife and those need to be respected if my wife is to retain any faith in me and value our marriage, but I do understand your recommendations and with more foresight I might have seen their value earlier.