let 婚姻 become a SEALED system first
then
no matter how long 男女仍然维系着很亲密的关系

why?

because 男 love to have 很亲密的关系 with 女,
I mean SEX, as such, wife MUST his only one partner,
otherwise, IMPOSSIBLE even a little bit leaking,such as,
porn, is also very very dangerous.

likewise, 女 enjoy to be treasured by her husband,
this usually could be guaranteed in a SEALED system
automatically, of course, man will treasure his only woman, however, if woman try to seek EXTRA, that means
she will lose both automatically. no man will treasure
whore too much and no man does not treasure his only woman.