Its easier to prove (but with more constrained consequences) than any crime, since its a civil tort and thus need only be proven by a preponderance of the evidence (loosely, whose story the jury feels is more likely true), not beyond a reasonable doubt.

May be easier to prove actually compared to normal consent based case as the default would be if the act was agreed on or started with a condom then taking it off would be an offense.

Uh huh? So my question is, how is it easier to prove that's the case?

So the lady needs some proof that sex occurred without a condom. Then she also needs to prove both parties agreed to only use a condom beforehand. She also needs to prove that the guy deliberately took it out. Maybe they could put it on the blockchain.

The civil preponderance of the evidence standard literally can be met by ”he said/she said" testimony by whichever party the trier of fact (jury or judge, depending on if it is a jury or bench trial) finds more credible.

It’s not a crime (I mean, the same act is already a crime, but that's not the law in question), so the criminal “beyond a reasonable doubt” standard of proof doesn't apply.

Easier in cases where disease or pregnancy occurs despite an agreement to use protection.

A verbal agreement? Wouldn't it just be a he-said-she-said scenario? Or do you think people will have a written agreement? And even then, diseases can spread even with a condom. And, I would presume, the perpetrator will claim it was an accident it slipped out.

Similar to the way most violent crimes are proven -- confessions.