My best friend is a guy (I am a girl) and he is involved in a long distance relationship with a girl he met (I'll call her Erica) when he lived in the Netherlands last year. Normally, me, him, and my other best friend (a girl we'll call Kelly) hang out together all the time. However, recently we hang out alone together a lot because Kelly just started dating another guy. I don't like him at all other than as friends, but it feels weird to me because of Erica. He's planning on moving back to the Netherlands after college to marry her (we're juniors in high school, and will be seniors when school ends in a week), which I know he's serious about because I've known him for a long time, and can tell when he really wants something.

Emotionally, I feel unstable about it simply because I know that if she lived here, we wouldn't be best friends, or hang out nearly as much. After all, when you get married, you can't have your spouse AND a best friend of the opposite sex. Is this unusual, or is there anything I can do about it?

Help would be appreciated,
Danielle

Nothing you can do but your right when he is serious with her you will not see much of him and maybe at some stage he may move and your friendship may end. Sorry but possibility.

Well, I'm only playing the devil's advocate, but it sounds a little like you might have a crush on this guy. Regardless of whether you have intimate feelings for this friend, you are emotionally attached to him, because he has been your best friend and closest confidant.
I do want to mention that, regardless of how serious he feels right now about this girl, his feelings may change at any given time... especially since you both have one more year of high school, and at least four more years of college. So, don't get stuck feeling as though you're going to lose him at any moment... you have at least five more years together!
Now, you mentioned that "when you get married, you can't have your spouse AND a best friend of the opposite sex" well... you can, and then you can't. It really all depends on the nature of the relationship between your best friend and "Erica". If they did end up getting married, and possibly moving back to where you live, there is a good chance that the three of you could become great friends. Not to mention that you will most likely be dating someone by that time as well.

So, try not to get too down about the situation. Again, it could change at any given time... and, if the two of you do grow apart, as you begin down different paths, you may find that you have a new best friend, boyfriend, lover, or husband-to-be-from-the-Netherlands.

Cheers,
Madam butterfly

Just enjoy your friendship, and don't dwell on what may be, as people and events, change rather suddely at your age, and no one really knows how things will work out.