It is perfectly possible for you to be poly and in a relationship with two people who are mono - there are many examples out there of so-called "mono/poly" relationships. I know, because I am in one. They take more work, but *can* work - my relationship configuration has been stable, now, for over 5 years.
Over the years I have felt a romantic affection for several of my friends. Some subtle conversations indiciated that poly wouldn't be something they would even consider, and I dropped any idea of ever having anything with these people.
Please check out The Birdcage - an open, friendly Polyamory forum for all parts of New York State
"Listen, or your tongue will make you deaf." - Native American Proverb