I have just bought a house to live in with my partner of 7 years. Not married, house in my name (he's got poor credit score) so legally speaking everything is in my name, when in reality we pay everything 50-50.
Not getting married any time soon, so we had a Declaration of Trust (DoT) drawn up to recognise that whilst the Legal Interest in the property is mine, the Equitable Interest is split between us. (Basically if we split we split 50-50 but I'm always legally responsible for the payments on the mortgage).
I think that there are lots of options these days to protect all parties. Marriage is just one of these options.
I really eventually want to get married, but I knew it wasn't going to happen in the short term so to protect DP I got the DoT drawn up. Otherwise I could have kicked him out and played dumb to the contribution he's made. Also becasue we're not married we've had wills drawn up so our wishes are carried out - without them everything would have gone to our current Next of Kins - parents.
Having just written all that out it has become obvious to me that we have done pretty much everything except saying I do.....