This is a classic water-fire dynamic, and it makes sense once you look at the core needs each sign has.

Cancer moves through attachment and emotional security - checking in isn't clinginess, it's how you build trust. Sagittarius moves through freedom and forward motion - space isn't distance, it's how they recharge.

The middle ground usually looks like scheduled check-ins instead of spontaneous ones. Something like a weekly 'us' conversation gives you the reassurance you need without it feeling like surveillance to them. It's not naturally easy, but it can absolutely work with intention.

omg this is literally my relationship. my sag partner isnt trying to hurt me by needing space, i just used to take it so personally

the scheduled check in thing MarcusAstro mentioned is actually genius, we started doing sunday night talks and it helped so much with the same exact issue