why is divorce not a sin?

when you call the police over physical abuse,you are initiating divorce steps.
when you do wrong,you rectify, then when you marry a criminal ,you rectify by divorce.
two people can not walk together unless they agree,marriage is walk where two have to agree.
when you a devil, you better withdraw.
when you 10 tooths from beating, you will judged ,guilty of stupidity.
patience has limits.
they say"let not what God unified get separated, however, many are unified by the taste of education,the greed of money,the lust of carnal pleasure,by same tribes,by political parties,tastes to sports,by same denominations,by physical muscle,by hights,by sizes, etc