You cannot remain in a one sided marriage forever. 

A person whose score was still high may have moved into my property at the beginning of a separation in marriage and a score that was about to plummet.Furthermore, I've rented what I think may be termed a "C" class property to tenants who surely had super low scores but I had no problem with the tenants paying.Although I don't have any hard evidence that credit reports and background checks are helpful, I would still recommend that you pay the cost and run them if you're in any doubt. 

Until you are both willing to commit to marriage, what makes you think you'll commit to any other contractual obligation?

My only concern is that you're committing to a financial contract with a woman you're not personally committed to in marriage.

Marriage is highly over rated.

It's really hard and it was a strain on my marriage.

Step-dad has a son from a previous marriage who has now become the heir to the estate as step-dad did not have a will.

I have resisted the idea as it's been a chaotic couple of years (marriage, two babies, two moves, both of us changed jobs, he lost his father, etc) and I've just wanted to be on cruise control when it came to our careers.

Under HUD Guidelines, co-borrowers needs to be related by law, blood, marriage.

@Nicholas Tanner partnering is like a marriage.