I am sure I will get ripped to shreds for saying this, but from her side, if she's become accustomed to a certain lifestyle married to you and has no marketable skills at the moment to get a job and support herself, why should she be punished financially because YOU want out of the marriage?
Assuming she's a SAHM, the four years makes sense so she can acquire the proper skills necessary to get a decent job, support herself and rebuild her life.
I do NOT agree with alimony being forever and I also don't believe it should be a mandatory 50/50 split IF a woman (or man because if the wife was the higher earner, SHE would be paying HIM alimony) has a career to fall back on and/or marketable skills.