In the world of relationships and Marriage verbal agreement means shit.It proves nothing.
Example: A hypothetical situation where a couple is married and everything was fine and oneday she left the house with verbal agreement.In this situation he thought it was done and moved on with his life and he started fresh everything was fine ,after couple years the partner is back from the dead started court proceedings and he ended up paying alimony and all the shit.
Even if the partner left with mutual agreement as long as it is not properly done through the court it doesn`t matter.