Pheonix - she knows about protection, and assured me that they're using it (pills and condoms both) - I'm mostly worried about the 7 years difference. I've got too many X chromosomes to be a male figure in anyone's life, but it's better than nothing, I suppose...
The main problem is that I'm not an expert here and she knows I'm not, and I know her doing this right now is asking for trouble, but I don't think she respects my opinion here enough to actually listen to me in this case. She's always had this symptom of being the younger sibling where she wants to do everything first and feel more "adult". She listens to her close friends, but they're all the same age and they don't see a problem. I see where they're coming from though, since when I was their age, I had a friend that was doing the same thing and I didn't think twice either. It's amazing how much wisdom you get in 3 years, if you can call it that.
Boomerang - he's worried about the family breaking up too - in fact a lot of our close relatives have been trying to keep in closer touch with us. But he's not really able to fix things any more than she is. They both act like children when they're around each other.
From what she said, she doesn't consider it a real monogamous relationship, and she's still going after other crushes on top of it. I'd love to bring my sister up to college, but it's on the other side of the country.
Lash - thank you for the advice and encouragement. (Really.

) I want to try and meet him when I go back home for the spring (about a week from now) and actually get her to introduce us to check him out and also so that maybe she won't feel like I'm not being open about it (and maybe she won't feel the need to be secretive about these things for 3 months anymore). I know she's going to be 18, and she's old enough to make some of her own decisions, but she's also going through her last semester of high school and I don't think she needs additional stress now, especially if he turns out to be some weird creep. I know I haven't done as well in college since my mom passed away, and she's having to deal with applying to universities and taking APs and so forth too. I know that she probably needs to learn some lessons through experience, but I don't want her to screw up her future in the process. A lot of my friends in high school wound up seriously messing up with drugs and sex and dropping out and I don't want to see the same thing happen to her.
And please don't use this as a reason to never argue with me again. :wink: I know I'm wrong at least some of the time, no matter what.