Hi there Dr Phil  and welcome to Big White Wall! Can I ask... why do you want to tell her to run for the hills if, as you say, her fella is not such a bad bloke? I am unsure from your post why your instinct tells you to encourage her to leave him? (if that was what you were suggesting?)

Otherwise, it sounds like your best bet is to just listen to her without offering direct advice (which may later down the line come back to bite you if it does indeed go 'pear shaped') I have learnt from my girlfriend that often she just wants to vent to me, and if I try and give her 'the solution' she just gets annoyed at me anyway... your best bet is just to make all the right noises in the right places to get her to keep talking, that way perhaps she will find her own solution without you having to offer one??

come back and let me know how you get along... good luck!!