No, let's really examine this in detail. It's about damn time.
I was once again inspired this morning by one of my dearest friends--lucky me, although ad money knocking on my door would be sweet, too. This time, the topic of conversation between the inspirer and myself was opposite sex friendships. Woooo, smokies, do we have a topic here.
Now, I will remind the reader that I am not talking about two single people--that's a whole 'nother can o' worms. I am mostly talking about an opposite sex friendship where at least one of the people involved is in a relationship. That's the key fact here.
Let's illustrate. Say that I have a straight, single, male friend. We'll call him Joe. I like Joe, because he's a funny dude, an interesting person to talk to, and a genuinely nice guy. However, I have a boyfriend, who incidentally happens to be the man of my dreams. Therefore, I have absolutely no romantic or sexual interest in Joe.
Joe and I hang out frequently alone. Our conversations get deeper, and on my end I am just happy to have someone as another friend. However, Joe starts to realize that his feelings for me go beyond friendship. Before I know it, Joe tries to kiss me. I push him away violently, but realize that I let the friendship go too far, and we cease talking.
Sound familiar, girls and boys?
Honestly, don't even try to tell me that you've never heard of this crap happening. It can also happen when BOTH people are in relationships, too, and--worse--the two people can actually fall for each other. Sound like something you wanna deal with? I didn't think so.
Now, even with example-a-plenty, this still doesn't quite make sense to a lot of people right off the bat. A lot of people feel that they should be able to hang out with whomever they want--it's a matter of "trust" in a lot of peoples' eyes. I can't disagree with that, but even still: you have to remember that even if YOU, the committed person, don't make a mistake, you cannot guarantee that the person on the other end won't fall for you. If they do, consequences range from their frustration building to the point where they act "weird" around you to they try and make a move on you, thereby jeopardizing your relationship and ruining your friendship. Not fun.
More people will say, "But I've known Jane/Joe forever! I don't have feelings for her/him, why can't we hang out alone anymore?" Obviously, I'm not of the opinion that you need to cease conversation with that person forever or start avoiding them. If you really care about your friendship and HONESTLY feel like there's no funny business between you two, then introduce them to your partner. Hang out all together, and then see how things go. I think this is huge.
What if Jane/Joe is gay? Obviously, WAY different story. I know full well that my gay friends won't make a move on me. You're probably in the clear. I would still introduce your partner just in case.
Speaking of LGBTers, if you're in a same-sex relationship (regardless of orientation), I would say that it's pretty self-explanatory that the rule is reversed. Duh. Don't hang out with the same sex alone, generally, but opposite sex is probably nothing to worry about. Again, though, introducing your partner is KEY!
You get the idea. It may be kind of a "case-by-case" scenario, but I still think the general rule is the safest one. If you haven't guessed, I myself have *not* had the greatest luck with partners and their friends, and I've had a handful of opposite (and same) sex friends fall for me while I have a partner. I'm not saying you can never hang out with someone alone while you have a partner, I'm just saying: think about the situation and whether it's truly appropriate. Like most things in life, this all comes down to judgment. Use your judgment wisely.