I don't know what happens if one of the partners were deaf with no usable hearing or is unable to use hearing aids etc. But I can say that one friend who has severe hearing loss (since birth), is able to get around in the hearing world (Better than me it seems lol) but works within the deaf world- deaf schools for most of her career. She married a hearing man (who I also knew). I THINK in the beginning he did try to learn some sign... before they married. After they married he barely signed all that much. From what I can remember, they did sign to each other but rarely (there is one incident that I remember vividly from nearly 20 years ago...not a nice incident either). I think the poor communication- both sign and verbal was one of the factors in their eventual divorce 16 years into the marriage. He never made the effort to go with her to deaf events(or work events really)- refused to 99% of the time.