Fruitbat;
I'm in my final year at university, studying law, and next year will start my training as a solicitor (queue abuse). i mentioned before that I studied family law last year, and we looked at divorce. I had a look at our text book and the relevant statutory provisions. As regards you friend's situation:
As I said, law in practice isnt necessarily the same as on paper, but the law as i have been taught it is that if your mate's wife has no grounds for showing that the marriage has irretrievaly broken down through his Adultery, behaviour or desertion, then the divorce can only be granted after a period of separation. This period is 2 years if your friend consents to the divorce, or 5 years if he does not want the divorce to go ahead. (but if the pair reach 2 years of separation and his Mrs still wants a divorce, is it worth delaying the process 3 more years?)
I am in no way qualified to give you legal advice, and I would not purport to do that, but that is the law as i understand it. I would again suggest that your friend seeks some legal advice before he makes any fixed decisions.
Hope it helps. Good luck.