For us it was time. It took time. As others have said, be patient, take your time, have fun taking things very slow, enjoy the journey. I was not at all looking to be with other women. I am crazy about bi male sex and sharing that experience with my husband. I had to give a little to get a lot, over time I got used to being right there with other women, more and more happened. Other women can teach you things you never knew you didn't know. I perform oral better than ever thanks to doing it with other women (and men) so of course we wound up in interesting situations. I do know when cum is involved, kissing other people, wherever that is (mouth, pussy, breasts, penis, balls, sometimes is a blur. I get all caught up in the heat of the moment. Addictions can do that to a person I suppose. I let what happens, happens, and the flow works itself out.
It took my husband even longer, but once he saw all I was willing to do and how much fun it was step by step along with me gave in. We absolutely have no regrets!