OK, so Faye has got Marten re-evaluating his actions, and his life, even, which is probably a good thing.
However, the logic is pretty screwed. Yes, his present life is consequent on his leaving California to follow Vicky; but that is, in scientific terms, the outcome of an uncontrolled experiment - there is no way to know how his life would have gone if he had stayed, or returned when she dumped him, or if he hadn't ogled Faye that day in the bar, or if she hadn't broken her glasses...
After all, for any of us, our present life is the result of the bad things that have happened to us, large and small, as well as the good ones - so in the end how can we even decide which were which? We are the result of the totality of our experience, not of any one or even a thousand parts of it, and Faye is correct in saying that the best thing we can do is value the result.