In every marriage, you come to points that just suck.
Either you have kids and then have no time for each other, you are buried in work, or something else comes along and makes you take stock in what has happened to your relationship.
And then you reevaluate.
Let's face it...whether its 4 years together or 20, you've both changed pretty dramatically. And sometimes, it's just not a good fit anymore.
When I dealt with my husbands "fuck up", which could really be any mistake, I tried endlessly to find books or websites to help me out and tell me what to do. I mean, either you know immediately that you are going to get out of the relationship, or you don't know. And if you don't know, then therapy is the only way to really have a shot at working it out, because you need a guide through this treacherous point in your life. One wrong move, and the relationship is over, similar to taking a wrong step on Mount Everest. And what does Mount Everest have?
A sherpa. You need a relationship sherpa.
A friend who has gone through a similar situation is great in a crisis. They can tell you the good, the bad and the Ugly. Things you need to be aware of.
But a therapist can help you identify and communicate with your partner. They can give you the tools to remain strong and supported, and how to make things better.
At some point in your journey, you'll know what you want to do. Stay or go. Or your partner will make up their mind for you. Either way, you'll come out of it ready to deal with life the way it has become. And you'll feel stronger in the end.