These two are intertwined, and I understand them. You are with her at home, and yet you want to be laughing and talking and venting and such with us. I can see why that makes her feel a bit jealous of this "thing" she can't understand.
I don't have that conflict (although the Pet Psychic may tell me otherwise if I asked her) and I don't know her, so I can't give you advice really, except to say that in a sense, it isn't any different that real friends that you suddenly wanted to meet and talk to after work every night for a few hours. If you can't include her, then you would be smarter to go home than to pull that very often.
2) Because it involves (some) single persons of the opposite gender.
3) Because she knows people who have left their spouses for "online" mates.
First of all, I will promise to end this problem as soon as possible! But really, this is a matter of trust and context. I am sure she knows many more people whose marriages broke due to "real-life" encounters at the office, but she has come to grips already, I would guess, with the fact that you have to have a job. We are a long ways away, and much less available to you than the secretaries at work. I think I can also speak for the entire group when I say that none of us go for married men, or married dwarves.
4) Because she thinks people obsessed with LOTR need to "get a life".
Maybe it is a weird hobby. I don't know if it will help or hurt the case to tell her that we all share things and ideas that are not just LoTR, because it is probably that "more" aspect that leads to fears 1-4.
I guess my advice would be to be more interested in her than us when you get home, but that I don't think that means you have to give us up completely, just make sure that she knows you share the really important stuff with her first. There is no rush to get back to us, we will always be here, even if it takes a funkle to catch up.
Right Suzi? ;^)
(She'll probably see this later....)