I think tolerance of another's multiple entanglements is more important component of poly than the desire to oneself have multiple entanglements.

Never mind tolerance, to me it feels better for its own sake to not be my girlfriends' only boyfriend. It was a surprisingly large weight off my mind to know that if I can't take her to Yosemite, or escort her to BENT SF, then she has other paramours who can do so. I know that I'm not personally responsible for matching every one of her sexual facets, just some of them, and that she won't be forever sexually unsatisfied if there's something I happen not to enjoy. If you asked me "Is it more important to your happiness that that your girlfriend be able to have more than one boyfriend or that you be able to have more than one girlfriend?" I might well reply "The former."