Two names on loan and deed, but one pays all bills. Equal owners?

[Jacob Barnhart]

I am going to start out by saying I know this is a bad idea. Unfortunately my girlfriend is not as logical.
I have just been denied on a loan after having pre-approval and making it close to closing on a home. The lender didn't understand that mine and my co-signers (my mother) income were both from self-employment and after he found out a couple months after giving him all this information and being approved, we were called and told he can no longer go through with it.

Needless to say, my girlfriend is very upset as this was going to be a primary residence for us to start a family (as well as a location for my personal training business). She is now trying to get a loan for herself with me cosigning for this property. Regardless of the fact that it likely won't be approved, it is just a bad idea if it was approved.

Here are my concerns and questions: No-one ever knows if their relationship will last 30 years. and I don't want to be in a 30 year contract with a significant other. She has little income, so I would essentially be paying the entire mortgage, insurance, taxes, etc... while she helps with utilities. I was fine with that when I was going to be the primary owner with my mom as the cosigner. But I am skeptical of paying off a house that isn't primarily mine. 
If things went south with the SO, would I have any extra rights to the ownership of the house if I am able to show proof that I have been the "breadwinner" and paying for the house mostly on my own? Or do I still have 50% or less interest in this house?

The only scenario where I would consider this is if, by paying most of the bills, I am entitled to most of the interest/equity. (Believe it or not, I'm not stupid enough to enter into a contract with a SO without a backup plan)
Thanks, guys and gals.