213:4 Even if the bride or groom’s relative died after they set up the chuppah (the wedding canopy), they are not permitted to have marital relations until after the week of shiva. Since they have not yet had relations and they are not permitted to do so, they are not allowed to be alone together without a chaperone. After the week of shiva, the couple has relations in order to consummate the marriage, after which they celebrate the seven days of sheva brachos.
213:5 If a relative of the bride or groom died after they consummated the marriage, they are already in the week of celebration. These days are like a yom tov to them and they do not observe mourning. There are further leniencies in that they are permitted to launder their clothes and to have their hair cut. They are only restricted in private matters. After the week of sheva brachos, they start the week of shiva. The thirty days of shloshim are counted from when they start mourning. Even though a yom tov that interrupts shiva counts towards the thirty days of shloshim (see 219:7), the seven days of sheva brachos don’t because haircuts are permitted.