Jehovah witness dating beliefs
Marrying a non-believer is highly discouraged for practical and biblical reasons.
Even people who are not Jehovah's Witnesses and belong to other churches would find it wise to marry someone who shares the same faith.
I do not know if there are any official sanctions against female JW's who marry non JW-men (the position against women is more relaxed, I think).
When they do marry, the same advice as given in 1 Cor. 3) Many persons who are baptised as a JW, fade away and become inactive (this means they do not go knocking on doors anymore for a period of 6 months or more).
Basically he advises to stick with your partner (1 Cor. So in that case, JW's are married with non-witnesses and have to do everything in their power to make the marriage work.
It is however not a disfellowshipping offence to date or marry a non-JW.
However, dating couples who are both Witnesses are not free from the dangers of immorality even though they both should have the same views on pre-marital sex.
There are different reasons why some sisters and brothers choose to marry unbelievers, either voluntarily or out because they have drifted away from close association with brothers and sisters.
It is also possible that two partners are baptised and only one of them (very often the husband) becomes inactive (and has a different outlook on life, becomes agnostic, atheistic,...). Also the relationship with other JW's can continue as usual, however some JW members might not be so cordial anymore with a person who has become inactive. JW's give a party and only invite the JW partner and not the 'inactive' mate.
It is also not very uncommon that young persons who are raised as a JW (and baptised) marry each other and once they are married both stop practising the religion.