Hiya Pearl (and Cosmicgirl),
I'm new to this forum as well and wanted to just give a welcome. I do understand a bit of how the two of you likely feel. My wife loves me and has little interest in having anyone else in our relationship, but I've had a couple (primarily platonic) "girlfriends" over the years and she's been quite accepting and friendly to both of them (they were both nice ladies) and she's been open to allowing a longer term, more intimate relationship with someone (I just haven't found the "right one" yet) but primarily because we have a close and very open relationship/marriage and she doesn't have much reason to feel insecure or not trust me.
Anyway, I'm just rambling, but overall I think that's basically the key ... if two people love and trust each other and desire to stay together, then there's really not a lot of reason to hang on too tightly but instead you can add to things.
I assume it would be similar for the two of you, but I'd ideally like to find someone that my wife could become close to as well, and like I said, she and the couple "girlfriends" I've had in the past surprised me at how well they got along and in a lot of ways it made me more appreciative of how lucky I am to have found my wife ... even if we don't share a lot of common interests outside the home, I don't know if I could have found someone who loves and gives as much to me as she does. It was more of a logical choice to marry her and less a matter of having that "chemistry" (which I still miss), but the logic didn't do too bad and whether or not I ever find my "muse"
, I can't complain much (there are definitely people in worse conditions).
Anyway, I wish the two of you the best and hope you always appreciate each other.