"Normal" is a relative term. It isn't normal to be a professional skydiver, they represent way less of the population than gays, yet we let those people get married.
It isn't normal to be a Nascar driver, they too represent less percentage than gays, yet they can get married and divorced at will.
Only 44 people have been President (43, one guy is counted twice), that is extremely not "normal", yet almost all of them have been married and many of them divorced.
"Normal" isn't a standard we use to agree to allow people to marry.
It isn't "normal" to be excited by power-play and handcuffs, yet people who do that can get married...