People grow apart.. Marriage like a job. When you are young, you are happy to get any.. then you are growing, and you want different things in your job. You are lucky if your ‘job’ is growing with you, i.e. you get promoted, you like your new responsibility, and such. If not, you leave the Company and look for another job. Else, if the Company isn’t satisfied with you, they terminate you and hire another person. This is normal a process. Why marriage should be different? We keep changing during our entire life. Two are lucky if they are changing/growing in the same direction. If not, at some point it doesn’t work anymore. One has to “quit” and to find another “job”.