As far as Christians,there is no such thing as boyfriend,girlfriend,only engaged to be married,which until they are married to not engage in any sexual activity,other than hanging around each other.
There is no such thing as boyfriend,girlfriend,for if not to be engaged to be married,then they have not made a commitment to eventually get married,and know they will get married.
The saints are supposed to have an attitude to each other that it is hands off,and no sexual activity,as the world casually does it,and boyfriend,girlfriend,would imply that there is something going on between the two,that is not a normal relationship as should be between saints,and even kissing,and holding hands,and holding each other,would be wrong.
If they are doing something together as far as closeness,that they would not do with any other saint,then it is wrong,for boyfriend,and girlfriend,does not apply in the saints world,only engaged to be married,which then they should not live together,or kiss,which I do not believe they should even hold hands,or hold each other with that closeness,until they are married.
How can boyfriend,girlfriend,apply,when the only thing God sees as right is marriage,and being engaged,knowing you will be married,why,because it is a commitment between two people,a covenant,which is only valid in God's eyes.