Getting kicked from Islam equals fast invalidation? I read that a look with passion while fasting destroys the fast. You said it doesn't...

I recently asked a question about looking at girls while fasting and would first like to thank you for that. Jazakum Allahu khayran. But I read that a look with passion while fasting destroys the fast. You said it doesn't. Does the narraration I read talk about only it's(the fast's) value in reward and it doesn't make it(the fast) invalid? Lastly, another question I asked may have been written badly. I meant to ask that If I'm fasting and get kicked from Islam then make shahada, does my fast become invalid? I'm sorry for the mistake. Jazakum Allah