I'd give him a copy of the yellow pages with tax attorneys.
If he wants you, tell him to show up with a retainer of $10,000 ($2,000 per year plus the OIC retainer) and his information for at the least the oldest year -- in person. No check -- return documents. No show this time -- no further appointments or communication allowed. When you complete the oldest year, have him pick it up in person with a check in hand to rebuild the retainer. Charge three times your normal fee: prep fee, rush fee, and way prior year fee. He has to keep replenishing your retainer, because you know 2004-2009 will be needed before the IRS accepts an OIC or even an installment agreement. Explain that an OIC has a down payment attached and that it is granted for doubt to liability &/or doubt to collectibility (guess that's not a word). A healthy 40 year old has earning potential and is not a good candidate for an OIC.
Discourage the girlfriend from marrying him!!!