Well, it's been a fairly long road for me. I have only just recently (6 months ago) started dating after being married and monogamous for a long time.
My spouse had a couple affairs over the course of our marriage, and six years ago found her way to tell me that although she felt our relationship was going great, she kept being attracted to other people.
I did some reading, and the two of us did a lot of talking, and we agreed to try being poly. It took me the last six years internalize the change. Over that time, my spouse and I flirted with others, talked about being poly but functionally remained monogamous. My spouse might say she was biding her time.
Then about six months ago, a friendship of mine blossomed into a romantic relationship, allowing my spouse to feel more comfortable pursuing relationships of her own. My spouse and I get very different things out of being poly: I tend to be more hierarchical and paced, enjoying the opportunity to explore relationships with women; she tends to lead with her heart and is working through some big issues (addressing past abuse, exploring bdsm, bi-curiosity, etc.).
I just wanted to send out love to you all for living your authentic lives. I hope to learn from many of you. I also want to be a force for positive change in New England-- we aren't all dull and uptight!