My brother says he would rather keep an open relatioship prior to his wedding.open relationship is an intimate relationship which is consensually 
That's cool,so why doing that?
it is often used to signify a primary emotional and intimate relationship between two partners who agree to have sexual relationships but not romantic relationships with other people
Wow! That's like sticking to each other like glue I suppose.But how could one of the partners in the relationship determine that?
Open relationships include any type of romantic relationship
So when was it recognized ,to be anything serious?
A form of open relationship is the open marriage, in which the participants in a marriage that is opened