mwha - a classic conundrum.
so i live life balsy - and my "advice" is going to reflect that.
First thing I would want to know. Does he REALLY see her as a "sister", now your gf mite think he does, genuinly think thats the case, but does he?
Easy to find out.
wait till it's just the 3 of you and he is getting some attention from her. And confidently grab your girl by the hips and kiss her. (proper Hollywood movie style, hell say something cheesy and romantic just before you do)
run your hands over her body a bit and grab her arse etc. make it 100% passion, obviously you will have your eyes closed.
open them and look your mate rite in the eye.
how does he look?
you will be able to see on his little face immediately whether he is thinking "oh c'mon guys, we were talking here, get a room or save it for later yea" or if he is thinking "I wish that was me she was kissing like that"
now wether he is on your girls case or not. it's sounds like this guy should probably be taken out of the equation.
No...don't look up agent 47 in the phonebook.
Get him a girl of his own. even getting him laid will do it.
if you can only get him laid. do so. find some slut, tell her he is really likes her, but is shy etc. get both together add booze, bob's your auntie.
then when you are toegether (you him gf) get him to talk about how he f**cked her. get him to give a few details and don't let him dodge the questions. (if your girl does kinda fancy him - this will most likely "break the spell")
next up and better
get him a gf - so find a clingy slut

once he has that..even if they have only been together for a bit....use the powers of female suspicion and jealousy in your favour.
be subtle - "ha ha must be great going out with "terry" and getting so many compliments all the time..."
"compliments all the time...no more than normal i'd say"
"oh well he's always saying nice thing about my "amber""
just plant those seeds. trust me, hook him up with the right kind of girl and she won't be having ANY of it.
next up...and as a tactic if you can't get him laid or that doesn't work.
use your noodle and engineer a situation where he does something really sh1tty to her.
the shittier the better.
This is best done with the help of someone.
example. friend says he will meet her at say 9pm to go see a film together. she asks if you want to come along, you say no.
then get a "true friend" to meet up with him before hand, and get him drunk / stoned and use epic peer pressure to leave her standing at the street corner like a douche. Also make sure while he is drinking...that someone keeps his phone off...
at this point...you need to make sure that YOU have an iron clad excuse for being uncontactable too.
she is gonna feel shit.
let down etc.
and when she says...
"you left me stranded at a street corner on my own, and you didn't even pick up your phone, I had to get back home ON MY OWN...i was so embarressed. how could you do that"
like an idiot your "freind" will reply "sorry i got drunk / stoned / whatever"
and this NEVER CUTS it...worse if he lies...you just call him out on his lie.
"what? but "bobby" told me you guy's were doing jeagerbombs in the irish pub that nite"
now he's unreliable guy who got drunk and f*cked a slut.
There are many tactics like this, It's the "offence" way of thinking about it. be the alpha.
apart from that, you gotta play it cool and act like you don't care.
reasure her, of course it doesn't bother me, because it's not like your doing anything with him right?
thats senario 1.
there are 20 or so more.
but that would be the first move.
see what he is really about
and either way. get him out of the equation.
also, on a final note.
if he doesn't see her as a friend. start the vibe going that he's always looking at her arse and her tits.
"i don't mind, it's just a bit weird is all"
and NO, he doesn't do it to other girls.
good luck
This post has been edited by Licentia Per Oris: Nov 13 2012, 09:03 AM