Not surprising at all, and yes they do seemingly "nice" things mostly because they want to appear "nice." It's all about projecting the appearance of being a good person, not about actually being a good person.
Now, this diagnosis really doesn't change your situation at all, it merely gives it a name. So, best thing to do is continue on your path of self-discovery and continue asking yourself the hard questions. For example, when you say you want this marriage to work, what are you really saying? When I said that to myself, what I really wanted was for *him* to change. I didn't want to make the marriage work by accepting him as he was. In other words, I didn't want to be married to *him*, but some idealized version of him I created in my mind.
L