In the United States, Canada, and many other English speaking countries, for some strange reason the priest or person overseeing the marriage ceremony would ask the bride and groom separately the following series of questions:
Do you ______ (bride's name), take this man who now holds your hand, to be your true and wedded husband; etc...?
Do you ______(husband's name), take this woman who now holds your hand, to be your true and wedded wife; etc;...?
For some reason, the person being asked these questions by the minister/priest/etc... answers "I do" if they choose to answer in the affirmative and agree to said marriage.
So in theory, that t-shirt is written appropriately if not grammatically correct fashion.
As for the male's shirt? It should read, "Will you marry me?"