I can talk to you from both sides of this
I was a model when I was in school, I didn't really care for it, I just can't stand waiting around, so I stuck to being a laborer... I've dated a lot of girls who were models, here and in Mexico, there she was mostly like a product specialist, she worked for Superior beer, Coke, Remy Martin, etc... Here the girls I've dated have done anything from runway to hardcore porn... I've also recently started doing some modeling, first just as a joke, since my younger brother wanted to get into it, I went along to the shoots with him, the photographer shot me and I posted on model mayhem, all of a sudden there was a lot of interest in me... Point is when I was doing this I was married and my now ex-wife had no problem at all with my shooting with other women... (I did a lot of that) like simulated shots, suggestive, even were both of us were nude... My ex was also 13 years my senior and she told me that after a few years, things like that won't matter anymore...
It's all in your head... I don't think it ever bothered me for any of my ex-gfs to shoot with other guys... If it did, I've long since outgrown that... Just give it time, soon you'll see how silly you're being...