gucciman has said it perfectly. If she is happy in a sexless marriage, she shouldn't expect ME to go without sex and that is why brothels, massage parlours and internet dating are blossoming. Before you accuse me of being a male chauvinist, which incidentally i am, it is VERY common to see on internet dating profiles of married women, that the love their husband and children, but he is not interested in sex and that she (the wife) is seeking excitement leading to no strings atttached sex.
Sex in a marriage is not important, it is ESSENTIAL.