Hi! That story sucks. I haven't been in a similar situation, but hopefully I am able to add some value.
I agree with phatryde on a lot of points: It sucks that you do the work in comfort/attraction and he "uses your work" to close, you've given him social proof and warmed up the girl(s).
I shouldn't blame it on yourself and I shouldn't blame it on him. Just learn from the situation and try to work out some way that this doesn't happen again.
I've once read a post from AFC Adam, so the following is his brains working not mine. Hehe except from re-typing it

An seduction has to follow a certain order:
Comfort
Attraction
Seduction
If you fuck up one of these things you will blow a guy out.
Example of my own:
We have:
- HBblond: A target I already gamed a little bit on a previous night
- An AFC with no game
- And a group of natural AMOG colleagues
HBblond was talking with AFC in the corner at the bar. The group of AMOG colleagues where partying, screaming and doing whatever they do

I spotted HBblond and opened a set near her to build pre selection.
After a few minutes HBblond spots me, I wave at her and she comes over to say hi. I lock in and tell her: "How cute, you brought your boyfriend with you tonight. It looks like he's all over you". Making him to available so he's f*cked.
I then start talking with HBblond knowing that my colleagues will try to AMOG me and try to profit from the work I've put in, since they can open her warm.
I then tell her something like: "This is such a fun night. I am out with my colleagues and I am laughing my ass of. They are all such players. Every night when they go out they always end up with another easy chick. It's hilarious, look at them go". I point at them and she looks at my group of colleagues.
This is the point at which one of them grabs her and starts dancing with her. I re-open the set I was talking with and I am laughing inside, because:
After 1 sec of dancing HBblond looks at me and sees me talking to a group of girls, she's trying to get back to me to continue our conversation. The AMOGs notice she's walking away so they grab her again, trying to dance with her. Which makes them fall into the category I've just described them as. She doesn't want to be seen as an easy chick so she walks of and re-opens me again. Oh.. and the AFC is still by himself annoyingly watching everything. Sometimes there are nights when everything just goes as you like
You can try to frame your AMOG-friend as someone who only hits on easy chicks for instance. Hopefully this will f*ck up his game enough so that you can game your chick. It's up to you to decide if you want to do this to one of your friends.
Also try to sit next to your chick. I expect that makes it a lot easier as well

Hope this helps! If you have any question: just ask!
Dutch Student
PS. The 'how to break out of the friendzone video' is really good by the way!