If you break a coffee cup and glue it back together, it might hold water again, but it will always have cracks.
Barry cannot keep resetting time until it is perfect; he must learn to live with the consequences and the "cracks" he created in his own reality. 💔 The Timeline "Cracks" (The Fallout)
Quietly discovers she is beginning to manifest ice powers, signaling her impending transformation into Killer Frost. 🔬 New Faces and Villains [S3E2] Paradox
When Barry returns to what he thinks is his normal timeline, he realizes his relationships are shattered:
Remembers his memories and speed from the Flashpoint timeline and hunts Barry down. If you break a coffee cup and glue
The central metaphor of the episode is delivered by Earth-2's Flash, Jay Garrick. He pulls Barry out of the Speed Force and uses a coffee cup to explain time travel:
The mysterious hooded figure who restores Clariss's memories and speed. He intends to give people the powers they possessed in the Flashpoint timeline. 🔬 New Faces and Villains When Barry returns
Cold and grieving because his brother Dante was killed by a drunk driver in this timeline. He resents Barry for refusing to run back in time to save Dante.