Alright, get your head out of the gutter, I promise we're definitely not talking about THAT, but I mean if you're looking for that, change a few words in the search bar and be on your merry way. This is the three-way relationship that involves you, your significant other and their (or your) best friend. Maybe this is just a me thing, but in my relationship it's never just the two of us. It's us and one of our best friends and I know this may sound weird, but we're almost not complete without that third person. We need her, she needs us, that kind of thing.
I have seen that more and more in the past few years relationships have opened up to include another person (hopefully not sexually, but hey you're into what you're into) and this person is a deciding factor on what things happen. They're the person that tips the boat either way, because we've all been in the spot where it's a 50/50 vote and no one is budging. However my question is; is this person healthy to the relationship?
With someone like me who's hard-headed and very hard to budge, this third person is crucial to actually making decisions for my boyfriend and I, because I simply won't give in. I never have and never will. Luckily Adam and I have our third person - the oh-so-wonderful Nicole. Nicole is usually the person who yells at us and says "LET'S JUST GO GET TACO BELL GET IN THE CAR I'LL DRIVE." and we all need that kind of positivity and someone to shake it up to keep the ball rolling. Nicole usually ends up deciding on what we'll do and is usually at our house most of the time that I should probably charge her rent... (and now I know she's reading this and going to call me and yell at me, love you Roley Poley!)
Now that I've given you a positive view of your very own three-way relationship, I can tell you there are many negatives to this. With a relationship of just two people we see that some things should just be worked out between the two, but when you bring in a third person sides can be taken and there's just a bunch of problems that didn't need to be there in the first place. From my experience someone will say something, the other friend will agree and the third person will feel ganged up on and it's just a huge shit show from there.
My point is: Be safe and smart in your three-way and always make everyone feel important. (I'm sorry I'm having way too much fun with the word play here.) It's very healthy to have someone else in your life to help the ball rolling and to change up the stalemate, but remember your priorities.