Thanks for reporting this. You haven’t misunderstood the system—v0.0.4 can stack Rivalry too quickly and does a poor job showing how to reduce it.
Apologize, Comfort and certain Boundaries or jealousy conversations can lower it, but the balance is off in this version. I’ve corrected this for v0.0.5 so repeated background events cannot keep piling it on, stable relationships gradually cool it down, and the relationship screen points you toward the correct repair action.
If you tell me which characters are affected, I can also check that exact pairing.