https://drive.google.com/file/d/1oZcD8XpxmfY4mked_H1uNSbloet868ZL/view?usp=sharing

Check out the image links above - see that look on Claire's face? That's when Frank lost Claire.

This is back in the good old days of season one, when Frank was still Whip (specifically, s01e09/"Chapter 9").

Claire had equipment stuck in South Sudan. Cathy Durant offered no help, so Claire asked Frank if he could do something, including going cap in hand to Remy Danton. Frank flipped out and then uttered the words, "I think I broke the bowl" while Claire was staring at him, cold as ice.

Because Claire was his bowl.

Frank was counting on her to massage two idiot Congressmen his way. She said "Sure, I'll do it," and she then went right ahead and did the opposite, encouraging them to vote based on their beliefs, because doing so supported the needs of her non-profit organization. In doing so, she cut the legs out from under Frank.

Now, sure, this was a long time ago. Frank would go on to make VP, and then, eventually, president. But, this precise moment, way back then, was the tipping point.