After 18 years of monogamous, fidelitous, marriage, my husband came out poly.
I identify very strongly as mono.
So how did I cross that line. Great question.
First- I had to put monogamy in its place. I had to ask myself the question "Who did I marry and love?" Did I marry and love monogamy, or did I marry and love my husband, the person. Yes, I loved being monogamous, but did I love that "relational state" more than the person I had it with. Another way to ask this is, "Would a monogamous relationship with someone else be better than a mono/poly relationship with a man I loved deeply and who loved me deeply?" In the end, I decided to stick with the sure, amazing love I had, rather than risk seeking exclusive mono with someone else. Mono wasn't worth losing my love.
Second- I had to embrace the change. I had to acknowledge that this was a serious renegotiation of my marriage contract. It was not what we had agreed to initially. Yes, I had every right to say "No way, this is not what I signed up for!" However, I had to keep in mind that my husband and I had changed heaps since our wedding- we are no longer the young kids we were when we made those vows (and Thank God). I couldn't possibly still be married to my husband as he was at 23 nor he with me as I was at 21. We have changed alongside one another, supporting one another. Our commitment to one another was not a promise "never to change", it was a promise to change alongside one another, and in support of one another throughout a lifetime. Would it be fair of me to have accepted all the other changes we've made (good and bad), but to reject poly?
Finally, I had to find my place in the new poly equation. I had to experiment a bit (which mostly consisted of trying a triad with my husband's OSO). I quickly discovered that I am strongly mono. Yes, it is important for me too keep that designation and title. It isn't just for a couple. I get to choose what I am in any relationship. I still get to choose to be happily, blissfully mono, even if my husband isn't. It is that freedom to be who I am that I have extended to my husband in being poly. I think it is hugely important for poly folks with mono partners to not only acknowledge their mononess, but to support it. In the poly community monogamy is often looked down upon or considered "less evolved". I really had to wade through feeling bad and beating myself up that I couldn't be poly.
The truth is I become a muddles mess in poly relationships, but I am an incredible, loyal, loving, unselfish partner when I am allowed to be my mono self. Why shouldn't I stick with the relational style I excel at?
Hope that helps cause writing it certainly helped me.