One of the luckiest accidents of my life was British visa restrictions forcing me & my girlfriend to decide if we were truly in love or just pretending.
Marriage is crazy. You’re right to think, “I’m not sure. What if it doesn’t work out? I lose so many options, etc.” It’s an impossible-to-guarantee decision with huge downsides. But if you do it right, the upside arguably approaches infinity. People postpone marriage for the same reason they're becoming less religious: we've lost the capacity for faith.