Haha, sorry my reply is not going to help, but I remember on one of my first big group rides, there were four of us ladies who were pretty new and decided we would break off and run the route at a slower pace. Rob came with us to ride sweep, and at every stop (seriously, EVERY stop), the girl leading the ride went straight to him and basically hung off him, standing too close, touching him while talking way more than you should with someone you just met, and that sort of thing. He didn't even notice (or at least said he didn't), but the other girls in the group were like, "Dude, really, his fiancee (at the time, now wife) is RIGHT THERE!" It helps that guys can be clueless

But, had she acknowledged the rest of our existence even half as much as his, it might have been seen less as flirting and more as connecting with a more experienced rider.
Anyway, I don't think I have ever run into this problem, but then again, I ride with my husband 90% of the time, so maybe they just don't perceive me as a threat....especially because on non-riding activities (winter get-togethers, post-ride BBQs, etc.), I find myself hanging with the girls more often than the guys. As long as they have something worthwhile to talk about that is....
If I were to give any advice on how to handle the situation, it is tough love, but first and foremost take an honest look at your own behavior. Are you doing things that would imply to a woman that you are trying to "get her man"? Are you acknowledging the girlfriend/wife's existence and trying to get to know her, too? Or are you only talking tot he guys because they can talk bikes? I'm not saying you are doing anything intentionally, but sometimes we get wrapped up in the whole motorcycling thing and don't think about the other people that are involved - the significant others, children, heck even pets, that are affected by this person's longing for the open road. I always try to learn my riding buddies' pets' names, and try even harder to remember the names of their sig. others. I also try to strike up a conversation that can get everyone involved, so that people do not feel "left out." Honestly, this may be what you are perceiving as jealousy....you are a potential buddy to the wife or girlfriend, and she may feel alienated by your "inability" to talk about anything other than bikes, which she probably has no interest in, and feels that she can't make a connection with you.
Again, I'm not saying any of this is actually happening, but just some thigns to be aware of. It it truly is jealousy (and sometimes it can be, I guess), then there really isn't anything you can do about it except keep being the riding buddy as long as you can stand it and hope the guys get it figured out for themselves.