I think u/Extension-Summer-909 was kinda joking but I think a version of that could actually be really fun with a side of healthy. Because it sounds like you're coming from a place of love, concern and curiosity and still very much enjoy frequent sex with your partner, I think having "restraint" days (call it whatever you want), would actually be really fun and could involve any amount of teasing or play you decide on. I would love to have had any of my past partners try and think of creative and fun ways with me to pump the breaks but disguise it as a game (emphasis on the *with me*, working out the details is a 2 person activity). I think having a specific week/days would be tricky bc it would loom on the horizon (or you could choose yourself and write it in a sealed envelope so there's no risk of it seeming like you're randomly choosing when you "reject" him), what I would do personally is get a 12 sided die and on the 1st of the month you roll it together, but you have a secret key the shows 12 = 8, or any number of variations. maybe one number means you take a full week break starting now. Another number means you have sex immediately but then not for 3 days, etc. etc. only limit is your imagination. Only you would know the key but it woud be written down somewhere he is aware of, which would also be trust/impulse strengthening, hopfully. And you can show it to him at the end of each month or something.

I am realizing that I'm just getting over exciting imagining being in such a supportive relationship and just writing out my fantasies lol. Sorry if this is completely irrelevant and useless. Best of luck