It's been years since I've looked into the legalities, and I know rules have changed since I came across...and possibilities are probably only going to get worse considering immigration is such a hot political topic over here right now. So I'm not even venturing a guess of advice.
You probably realize that it's not just the relationship you're talking about. You also have to like the country. You can pretty much "get" a relationship in six months. It takes 2 years to be sure of the country. And by then you've given up a whole previous life to the point of there being nothing to return to.
I just wanted to offer a chime-in with the frustration. I was in your shoes, and I felt the immigration laws actually forced my now husband to propose to me, and for us to get married before we were totally sure, only to have me stay here a bit longer to get to know each other more. It's just plain wrong. But, you've got to play by the rules regardless if, in the future, you may end up unhappy, divorced and (whether you planned it or not) possibly being supported by the country because you've found yourself homeless.
I'm a happy ending. It worked, I love it here, I love my husband, we grow stronger together every day. But for x number happy endings, there's x number failures. And the country does end up providing support in many, many of these cases.
I'd like to see immigration laws change, but not in the way the politicans are proposing. They need to change with the reality of the present, not with the hysteria of emotions.