What you replied were
already expected; and what he should do, I already replied.
You mentioned that B and G acted like real couple - that's his main
problem. His changeability nature - initial thought of having a
fling, now change that rule because he feels she can be a good gf.
The rule about fling is that, once we had our fun, byebye, lets
move on with our life. He didn't. He change that rule and
implicate his current relationship. 
The fault begins with him and it has to end with him, using his
initiative.
I think G is like a lost sheep.. he wanted to pull himself out
of this sh!t n also help the gers but he just cldnt do it...
There is no best of both world methods. Being a Cancer, he would
want all parties to be emotionally satisfied - no such idea doesn't
exist in his context. I mentioned before and would repeat again -
he doesn't want to be the bad guy and rather circumstance
lead this current situation. Tension will build up one day
and either one of the girl will initiate the break up even if he
does nothing.
Let me tell you, sucide is not born of the girl's character -
rather is his lack of duty as a bf that created such effect in
their behaviour. He is the SOURCE of their dispair
and the stagnant of leading a futureless (if there is a word)
relationship is depressing. I give you one very good example:
Even B, tried attempting sucide after entering into a
relationship with him. I would understand that inferior
complex of A could do something tootpid (virgo, mental)- but if
BOTH parties were to react the same way, don't you think such
behaviour are actually factors and influence from his
behavour of leading the badly-lead relationship?
You said that he tried very hard - but is it effective? Trying
speaks half the story - it has to be effective. Therefore, simply,
the old ways of handling is wrong and must be improved. He has to
consider my choice of advice if he wants the better of the three
(in my previous post.) The day when he don't mind being the 'bad
guy', would be the day this thing can end.
Cheers
