Does this make me bi?

So me and my best friend have been in a relationship for the past 4 years and we've basically grown up together. I've realized that from the time we first got into the relationship I have had absolutely no emotional attachment or need for her, it's purely physical to me but I'm not even that interested in the physical aspects of it. She always tells me she loves and wants to be with me for the rest of her life, but I really don't want that and I've told her that. I'm not sure why I even got with her in the first place.

We get boyfriends every now and then when we get interested, which is what I think is odd since I'm perfectly ok with that and it's pretty easy considering we're not open about our 'relationship'. So am I bi or am I just doing this for the hell of it?

Bi as a label can mean as little or as much as you want it too. The label covers sexual and/or romantic attraction to both men and women. Sounds like that's where you're at right now but your attraction does not sound equal.

Maybe if you were to look at Kinsey's scale you'd rate yourself as "Predominantly heterosexual, but more than incidentally homosexual". Use the label Bi if you want but it's up to you, other people are not in a position to label your sexuality.

Well, you could consider yourself bi or you could consider yourself not. You said the relationship is purely physical, do you find yourself physically attracted to other women? Bi can mean anything from being emotionally and physically attracted to both sexes, to being physically AND emotionally attracted to one sex and only physically OR emotionally attracted to the other, or any combination of the two.

Honestly, you don't have to label yourself anything if you don't want to. However, I understand the feeling of wanting to label your sexuality so you feel like you know that aspect of who you are.

Here's what I would do personally. If you don't find yourself attracted to other women, just her, and have never liked any other women in your life, I wouldn't necessarily consider myself bi. Alot of straight people are attracted to someone of the same sex at some point in their lifetime, but it doesn't mean they aren't straight. That doesn't mean you can't accurately label yourself bi, if you feel like that fits you.
My last bit of advice would be to think of this: if you know for sure you like men (which I'm assuming from the bit about occasional boyfriends) think of this. Compare if you like women the same way you like men. Do you feel the same towards them emotionally, physically? Can you see yourself in a relationship with a woman (other than the current one)? Things like that. Good luck.

Sorry I couldn't be more helpful, but with things like this only you can truly figure it out.