will Niall merry me for real no or yes

It depends on if your're nice and niall said he would total date a fan

if you are nice he will probably date you ;)

It depends if you will do anything for him

You never know what'll happen in the future.
Life has its own way of telling whether you'll get married or won't.
Just at least try not to take it the wrong way if you don't get married to him.
But who knows.