We are both hard to live with in our own quirky little ways and would have needed a test run. Neither of us believes that being in love makes a person "live-able." But that's just us. We're cranky "rose-colored glasses smashers".. Personalities like ours need test runs!
You hit it right on the head. Dating someone and living in separate places is totally not the same as having someone in your face 24/7. It's a huge adjustment and an exercise in compromise.
I'd never consider marrying someone I hadn't lived with for at least 6 months, but that's just me...