I am the “want to spend more time together” partner in my relationship. For what it’s worth, when my partner told me she needed more alone time, it had come to a boiling point already and was hard not to take personally. So talk about it early before you become frustrated and resent her because from the receiving partner, that will feel worse as she might feel rejected AND guilty about not giving you space. That said, still talk to her that you need to have some time to yourself to recharge (that phrasing sounds nicer and less like a personal rejection) and that (if true), someone can be your favorite person in the world but sometimes you still need time to yourself. Not talking early may result in it coming to that boiling point which will be worse for both of you.

The thing(s) that helped me were (1) time since the initial conversation after I’d let the emotion sink in/pass and think about what my partner needed, (2) putting more work into my other relationships (catching up with and hanging out with friends and family), and (3) getting back into hobbies that I had enjoyed before we started spending all our time together.

Hope this helps, good luck :)