The million-dollar question here is whether your boyfriend is genuinely shunning marriage because of his financial situation -- which actually may be a positive sign of maturity -- or because he really does not wish to get married. If it's strictly the financial issues you list, perhaps you both can see an attorney who specializes in bankruptcy or family law to make certain your assets can be fully protected if you marry. State laws differ, so it's critical that you take this step and not rely on message boards.
Some avenues you might discuss with the attorney:
1.) Keeping all assets in your own name exclusively. 2.) A prenuptial agreement that protects your assets. 3.) Keeping credit cards in your own name. Caution: Although you can make your spouse an "authorized user" of your credit card account and get credit history on the card reported in his name, you might not wish to take that route if your boyfriend has not fully corrected his abuse of credit. Reason: You'll be responsible for all the debt -- including his!
It also is important that you be aware of exactly how much he owes. Then, perhaps, you jointly can figure out a way to pay it off and rebuild his credit.
Here's the ammo you requested: Your good credit actually could help him qualify for a mortgage on a house he otherwise might not be able to get.
Warning: Debt and credit problems are a chief cause of stress in marriages, so it's wise to seriously consider these issues -- before you tie the knot.