You can tell your fren, if she is a BI, still got chance...
If les, a bit hard. If below 20 still got chance to change back. above that age... can really forget it unless sometime with a super big impact on her changes her mind to go back to straight.
I once know of a girl, who has been les since young became straight again at the age of 27 coz of a very big impact on her ( Her mum commit suicide in front of her because that girl does not want change back to straight. )
That was a very sad case.

Ok.. back to topic...
Well, your friend got to check whether is that girl a real les, just started or still under unkown catogery.
If just started or unknown, can still got chance.
If pur les, go find another girl.
But under typical guy response to this question would be:
Save your prick for another girl.
Dun waste it on them lar.. waste str8 & time.
