Does the ERE still revoke your titles even when his relationship with you is positive?
I only have experience with the HRE, where I last played a Dutch Cathar (female) duchess of Flanders who eventually became queen of Frisia. She started out as a countess in Zeeland, and took the titles of Duke of Flanders and Holland by force. Both had become independant earlier, which ment the emperor had strong claims on both. With four maluses (female, foreign, heretic, claimant) his relation was always negative, but he wouldn't actually start (spam-)revoking until around -35. His heir inherited weak claims to both duchies and would also start revoking around -30 to -35.
I kept it above that by marriage, education, gifts and diplomacy by stationing my chancellor on the capitol province to increase relations. I also joined his wars (relationship bonus) and refrained from joining factions aimed against the emperor (side-stepping maluses).
Stationing your chancellor there means you can't fabricate claims, but at least it's better than having to deal with your liege either revoking titles or declaring war on you. The third option, igoring the demand until he dies, is too gamey for my taste.
I'm not sure of this applies to your situation, but it might be worth a shot. This does require keeping a keen eye on the situation, though - sometimes his relationship with you can drop suddenly because of other events. Also bear in mind that marrying and being educated by Greek characters will have an important influence on the culture of your offspring, your chancellor increasing relations is random and can also backfire, and gifting an emperor is never cheap...
As I said, it's been a couple of months, but back when I last tried he revoked titles even if I had 50+ relations with him..
Anyways, gonna give it a try again in not too long