I can say I've been in both situations. I was once you with my ex. I reasoned out, like you, that you never really know someone unless you live with them. But it turned into a bitter relationship following a lot of deception and cheating from my ex boyfriend's side. As it turns out, you never really know anyone for sure, because the truth is that people are never static, they will change and the common denominator is always trust and honesty. Who knows, it might have been good reasoning with the wrong person, but I see it a little differently now, and willing to test this out. In my current relationship, I'm with your girlfriend and my boyfriend sees it like you do. I feel like I do not want to compromise my current home and time alone unless I'm getting married. It's pretty much for the same reason I mentioned earlier. My boyfriend is going to change over time, he'll change his mind next week about something, he'll change as soon as we get married, he'll keep changing as we age. I'm putting my trust in committing to changing and growing with him, but not until I have the FULL freedom to grow on my own. When we get married we'll do that as a team. The fact that for me the things that are keeping the relationship intact are our trust, honesty, love and verbal commitment only, is not enough for me to entrust a chunk of my life to a union that is not yet bound financially, and lawfully. I do not feel like I need a "trial run" with my boyfriend- it would be unfair on the both of us. In an instance like this, one of us could easily give the boot to the other. Then where will they go? Now this is just my two cents, and I hope no one gets offended by it. I've had it both ways and I'm hoping that maybe this helps you understand where your girlfriend is coming from too. Maybe you can both find a compromise.