A women told me if you get married and don't have sex.
He did not fulfil his marriage obligation and they are not legally married
Never hear of this before

They did not consummate their marriage.

If the marriage was considered legal when it was performed, it's legal... with or without sex. There can be a number of various reasons a couple may not have sex.

Just to flip the script, having sex would mean you are married right?

Legally they are married.

Thanks

Sex, or lack thereof, does not trump law.

However, if the marriage isn't consummated and the couple decides to split up, in most country's they would qualify for an annulment instead of a divorce.

In some cultures, and in some of the "old" days, having sex was considered the final act of the marriage. But then there was not state license, or government license. The man went to girls home, and brought her to his home, they had sex, and lived together. That made them married. It was all part of a large celebration and party.

In fact in some cultures, the bride and groom were "watched" and in some since girl had to be a virgin, her family keep the cloth with blood to prove she was a virgin.

So at some places, at some time, this was part of the law.

It is also reason to have marriage annulled or grounds for divorce in some places.

But in basics, it is a old old custom, that has no legal bearing today.

With some religions, if Impotence is the issue, you may have grounds for an annulment.