in my experience, falling OUT of love with someone happens. It usually happens when you start falling IN love with someone else. And as a general rule you can fall out of love but still love someone and care for them.
There is a difference between loving someone and being IN love with someone.

I do agree though, you are married, you have a child, if counselling is an option I would do that. I believe you have to before you can get a divorce anyway don't you?