There is always something special about the first time you do something, regardless of whatever it is. No matter how many times you do that thing afterwards, the feeling you get when you do it for the first time is not easily replicated. Love can be an exception to this sometimes, if it remains strong forever. Daya is saying that her time spent with her lover is extremely special and precious to her. Every second she spends with her lover is like the first time she met them, meaning it is just as precious.