Depends on what state you are in. Most states are "no fault" or nearly so, so the reason really does not matter. My divorce complaint reads "complete incompatibility of temperament" LOL.
"Unreasonable" behavior is of little use, at least in my area. The court does not care - their job is to make things equal between the parties. The only time behaviors matter is if there is a custody fight (you did not mention kids) and then the court does what it needs to do to protect the kids.
Yes, no point in lining their pockets but a person who defends himself has a fool for a client. Do see a lawyer anyway for your own protection. The first visit is nominal cost and you can ask those questions that you need to know if you decide to do it yourself. Don't know what to ask? Visit any bookstore and you will find many books on divorce.
