I'm currently in the midst of planning a two-week solo holiday for myself to visit a friend in Switzerland, and my partner is planning a similar solo holiday for himself with his good friend. These solo adventures are something we've each had in our relationship from the very beginning, and they've proven essential to our personal happiness and romantic connection. I admit that spending that much time apart may be extreme for some couples, but we both thrive in having personal experiences and, as result, our relationship does too.
Spending time apart might also mean taking an evening or a whole Saturday to do our own thing, having dinner with friends, or pouring our time into a personally hobby. While we love hanging out, that alone time gives us the chance to miss each other. It provides us with experiences to talk about, and knowing each other has a strong sense of self is super attractive.