"I'm not going to intrude on your marriage" or "I'm not going to eavesdrop..." might be a better way to re-phrase the meaning of this one. The spirit of the phrase is that the other people's marriage isn't the business of the one speaking, and so they are going to stay out of it. Remember that tip-toe means to walk on the tips of your toes, which you do in order to walk very quietly. Thus, you're trying to either spy on someone, sneak up on them, or not disturb them. A more common use is "I'm not going to tip-toe around it, so let me just say it." This means that you're not going to try to be diplomatic, but rather very direct and blunt.

I may be wrong, but I have to disagree with the answer provided previously. I believe this has nothing to do with getting involved in someone marriage, in fact it means the opposite. I believe the person is saying something like this: "You are already married. I am not content to have a relationship with you that is secretive and hidden." The tip-toeing means that the person has to be secretive and quiet, but the person does not want that kind of relationship, the person does not want a secretive relationship, so maybe they are saying 1."It's over" or 2."You should get a divorce so we can be together" ? Or maybe I'm completely wrong! It is hard to know without knowing the context.

Actually, I think that watching movies with subtitles or closed captioning is a good way to start learning a language. However, I feel that I rely too much on the subtitles and, if you can understand foreign movies without the closed captioning, you probably will advance more quickly. I certainly wish my listening abilities were good enough to walk away from the subtitles.