I've got a slightly different perspective, being the wife in our riding duo - although our situation was a little different in that we went through MSF together and started riding at the same time. After moving out to California, however, I really got into riding, and he pretty much just stuck with commuting. I've finally started dragging him out for the fun of it, and he's gotten a lot better a lot quicker, partially because he not only was willing to listen to my advice, but also took it and used it. Not fair! What took me a few years, blood, sweat, tears, and time in the saddle to figure out, he managed to assimilate in about 1 year
My advice from a woman's perspective: don't give advice unless it's truly needed (ie very dangerous behavior) or she asks for it; hook her up with other people to ride with and other newb friendly groups; let her take the reins and lead you around places and afterwards, keep your mouth shut unless she asks for advice - and then, keep it concise; still keep riding your rides even if she can't come, otherwise, she'll feel like she's holding you back.
As for the feelings of trepidation - you'll have that no matter what. We (as a couple) have been riding for over 7 years now, and I still have a (mild) worry every time he gets on the bike. I would imagine the same goes for him. We don't voice this to each other, it's just something you have to accept. I do find, however, that I worry about him less when we are together (even if we're in different groups and can't really see each other) than I do when he's alone. Find what you love about riding, and allow her to find what she loves about it...it's okay if you are into different aspects of riding (something I'm now working at getting better about).