Jessica and Eric live in a small condo and have everything they need, so they chose not to register anywhere. Soon after the wedding, Jessica and Eric will both be full-time students. For a solid 2 years, they will spend every penny they earn paying for school and bills. It will be difficult for them to save for a honeymoon (Bali? Peru?) any time soon. If you would like to give a gift, they ask that you donate to their honeymoon fund.
Of course, if you wish to bestow a sentimental gift, they would welcome it.