In the Fushigi Yuugi anime on episode 19 Tamahome is under a spell which does brake?

You are referring to the scene where Tamahome is under the spell of the Mirror Demon in episode 19 of Fushigi Yugi.

While it's true that Tamahome is under a spell, it's not a spell that breaks. Instead, the spell is lifted when Miaka uses the power of the Suzaku's star to dispel it. The Mirror Demon itself is defeated in the same episode.

It's important to distinguish between a spell being broken and a spell being lifted. In this case, the spell is lifted by an external force, not by the spell itself breaking down.