There is no way you could be contributing to my marriage going south, even if you wanted to. The wife is taking care of that all by herself, and if you had a need to help in some way it would be of no importance to her.
It is ok to think about all the history you have. In fact, if you think about it in a healthy way, it will probably make you a better person. However, which history is more important???....the history that you can look back on, or the history that you have not made yet??
That pre-marital education is a great idea. Unfortunately, in my situation is would not have mattered. Before we got married, I discussed with my wife, repeatedly, how important sex and physical intimacy were to me. How important honesty and respect were. She agreed, and said that she felt the same way. As it turns out, she didn't.
I understand your guilt. Nothing is more empty than knowing that everytime you make love to your wife, it is only you who actually WANTS to be there.