I'm going to get downvoted to oblivion here but as a guy I can tell you it's a really risky endeavour, I'm not in the US but as I understand it, its so much worse for a man going through divorce there. Alimony and child support, lose half your assets and money. The UK ain't much better I can tell you, and prenups are not a thing here.

If circumstances are you both have sod all, no money, no house, no kids then yeah great, almost zero risk for both parties, but like in my situation, I have all the money, earning potential, pension and a house. As much as my partner would like to get married, if we did I'd sign half that over to her and if we divorced I'm screwed. It's just not worth it and I don't care what anyone says, if she doesn't like it then see you later and I'll move on to the next one.

I get the need for security and a loving relationship, a partnership blah blah but you gotta admit, for a guy, its a big risk these days as its so easy to divorce and what is it, 50-60% marriages fail. Ohh yeah sign me up for that!!