Song information (From Wikipedia - You're Still the One)
Unlike many of her other singles, "You're Still the One" is based on the true story of the romantic times and trials between her and Lange, and how the relationship was able to survive.[original research?] When Twain and Lange had become romantically involved in the mid 1990s, there was criticism of their relationship: claims that the age difference was extreme, and that Twain was solely using him to further her career.
In essence, the critics did not expect their relationship to last. However, the relationship has been able to survive, Twain disagreed with these criticisms and wanted to address them in public and this led to her writing "You're Still the One".
In this ode to the union between her and Lange, Twain explains how she is glad they did not listen to the critics, as if they had done, look at what they could have been missing. However, that is not to say that their romance is dead just because they are married now.
If anything Twain believes that the romance is just as strong as it was before, causing her to belt, "You're still the one I run to, the one that I belong to, you're the one I want for life".