Why does my boyfriend prioritize his female best friend more than me?

[Amanda771]

I am an 18-year old girl. Why is it that my 18-year old boyfriend (who I met when we were 17-years old) seems much closer to his 18-year old best friend (who is a girl) than me? It seems like he is just using me for sex.

No matter how much I try to convince him to spend more time with me, I am always unsuccessful. My boyfriend and I only spend time together 2 days a week and 2 hours a day. He and his best friend on the other hand spend time together everyday and they are together 9 hours a day. They even exclude me in some activities and some trips.

By the way, my boyfriend's best friend is straight and single. She is tough and strong like my boyfriend. They are not related to each other by blood. They help each other out in a lot of things. She also cooks many delicious meals for my boyfriend and she is very good at it while I can't cook.

I then got into a fight with my boyfriend regarding how he often prioritizes his best friend over me and he got angry. He yelled to me this, "You may be my girlfriend but no matter what you do, there will always be roles in my life that you will never replace, be equal at, or be better at than my best friend!!! Those roles will always be hers and will never be yours!!! Even if you become my wife in the future, it will still be that!!! She will always be my one and only best friend!!". I was upset.

I also heard him say something to his best friend when they were having a conversation. He said, "I want to be selfless. If you are in danger, I won't think twice about sacrificing my pleasure of being with my girlfriend so that we can fight together and die together. I will gladly die for you. I am your warrior.". I was confused.

I asked a cousin of my boyfriend why my boyfriend and his best friend are so close. The cousin said that my boyfriend and his best friend have been platonic friends since childhood and that they have protected each other from jerk tough boys, emotional sadist girls, etc.

Seriously, what should I do?

[quaranta]

I tend to believe their friendship is genuine, I have a lot of male friends but especially childhood male friends feel more like siblings or family members, their presence is "obvious", it's not like at some point you picture it finishing, wether you see each other every day or not.
I and my best friend (who is a guy) are very close too and his role won't be replaced (and wasn't replaced by any other guy I dated in the meanwhile), but there is a kind of unwritten rule that when we get a partner, we'll communicate more with that partner than with each other in the daily life. That doesn't mean stopping at all, just a bit less, which includes being less focused on each other.
The problems you are struggling with are the "main person" aspect. Typically, a partner is your "significant other", the main person you refer to. It's understandable that you feel like he keeps you only for sex, if his "main person" is another (regardless if it's a she or a he). He should understand this priority "rule" because otherwise that would give him the same problems with any other partner, if he keeps his best friend on this "significant other" pedestal.
I think things will fix automatically to some extent if she gets a partner too, but anyway he should carry the responsibility to manage his relationship with you in any case.
Ask him if you are his main person, and respond that he is your main person. If you aren't, then you are not on the same page and you have a different view of this relationship, going in disadvantage for you. That means you might have to break up at some point, probably, due to incompatibility in the vision of the relationship...

[Amanda771]

What about this part he said to his best friend? I am talking about this, "I want to be selfless. If you are in danger, I won't think twice about sacrificing my pleasure of being with my girlfriend so that we can fight together and die together. I will gladly die for you. I am your warrior.".

Seriously, what does that mean? And what would you do if you happen to have a boyfriend who said that to his best friend (who is a female)?

[quaranta]

Yeah that's something you'd say to your main significant other (it sounds like something he said in a situation when she felt the need of support?), so I think for him the "main person" is her even though they are not romantic or sexual, and don't plan to, most likely, but still... It remains the point you are giving him a role in your life that is not reciprocated, this has to be addressed (changing it or leaving the relationship) or you'll continue feeling like the "second one", or like just used for sex.
We can't exclude he is in love with her anyway but you said she is strong and they are friends from the childhood so this is really not granted, it sounds more like "bromance". And anyway regardless, the effects are the same: you don't feel reciprocated in the role in this relationship and that can't continue this way.
By the way, would he tell you similar things? Impactful and dedicated like that?

[Truth0225]

Sounds like they are in love to me. They just don’t wanna admit their feelings, and you have to consider, do you want to be the third wheel with your boyfriend forever?

[Amanda771]

Are you sure that they are in love? What do you think of my boyfriend's female best friend?

[Truth0225]

I think they are in love but havnt admitted it to themselves yet, and I bet she talks shit about you when ur not there

[Summeroflove]

If you’re not married having sex. Yeah he’s probably using you and who knows could be cheating

[noohair]

I have learned that in life, the only person you have any chance of changing is yourself. Good Luck.