It truly is. I see it as a good thing because seeing so many other stories turn out to be as textbook as mine is gave me a lot of hope and good ideas about what to expect, but of course it's terrible (and kind of chilling) how common it is. And just how easily it can happen, too! In a way, it makes sense. When you're the unfaithful S who is dealing with the harsh realities of M and dealing with your own problems with self-esteem & happiness, it seems like it makes you all too vulnerable to getting sucked into an irrational fantasy relationship with someone else. And, given that the A continually is compared to being on a drug, it's hard to extricate yourself or see things clearly once you're in. Just have to wait until the high gets stale and reality inevitably sets in.
