I'm a new member here and, Embers, I don't really know you. Many seem to respect you very much, though. I wish you well and hope things turn out for you.
As far as marriage goes, I just can't see a valid reason to exit but for some sort of exigent circumstances like violence, severe deception, abuse, or some type of danger. To me, this commitment is for life. I certainly don't want to speak for anyone on this forum, but some people I have encountered seem to feel they are entitled to happiness and feel the urge to turn away when things get difficult, when the "magic" is lost in a relationship, or they don't feel as good as they once did.
Entering marriage doesn't guarantee happiness. Ideally, two people should ride off into the sunset, eating ice cream and laughing. Most of the time, though, shit happens. There are bad times and people change. I think, however, just as things can sour, we have to hold hope that they could just as quickly/slowly swing back in the other direction.
FWIW, I have been married almost 20 years. We have four children. My wife is a saint, but even still, we have a lot of rocky times/ups and downs. I am also a Christian, so there are religious layers to my thoughts.
Again, I can't speak for anyone here specifically, but this is just something I have noticed. Also, again, I hope things work out for you, both for your health and your happiness.