sadegh1979: I think it is clear why a man and a woman go to bed, if they are playing cards there, they may have sex later, and common friends don't play card in the bed I suppose, especially when the husband or wife is out.
I don't know about your home, but here the rooms are quite chilly and the bed is a big flat and cosy place. Great for a set of backgammon, cards or possibly sex.
I would be sleeping very bad at nights if I needed to worry at all times what she do in that bed when I am not around. So I don't.