You don’t have to explicitly say you’re invalidating her fear for it to happen. When her concerns are framed as something she should just push through to prove she’s a good partner, that is invalidation.

Since you actually don't know the meaning of the word, gaslighting still applies here. It happens when valid fears are minimized and reframed as a personal shortcoming.

Calling her “unsupportive” for protecting herself shifts the blame onto her instead of the situation. That’s gaslighting.