It is okay to kiss someone after a rhinoplasty. The tip of their nose is going to be swollen and tender for approximately the first month or two. Any pressure on the nose will be painful to the person who had the rhinoplasty.
In the first few days following rhinoplasty a splint is being used to protect the delicate nasal structures. In the same time there is some degree of nasal obstruction from the swelling of the mucus menbranes on the inside of the nose. This could make the patient a mouth breather for a short time. So i guess the answer is you can but make sure you do not suffocate her or displace the splint!!