What if you... did this. Every Saturday and every other Wednesday? Don't tell anyone... I mean... on the outside, keep appearances as though you would like to keep to the schedule to Wednesday and Saturday... but only approach enforcing the boundary every other Wednesday...
That way... you are not backing off your boundary and potentially allowing him to slip back into old habits... but you are not the sex police and applying constant pressure, either. And if you only end up having sex once during the off Wednesday week... fine. If he hints at in some way, do it (and then say to yourself, i don't have to enforce the boundary now for another two Wednesdays) If he doesn't step up on a given Wednesday, and you are okay with it... let it go. But every other Wednesday... hold him to it... if you have to.
