"I'm sorry for putting you in this situation. If there were words I could say to express what's in my heart, I would have said it before, so you don't have to end up in this place, alone."
The ambiguous sentence that John just said might have comforted his nervousness, if only Clara was still a class X girl who only knew puppy love. Unfortunately, she is now a grown woman who has started to know love, and Clara admits that it was John who first taught her the true meaning of love.
Not Blake.
Because when she loves Blake, she becomes willing to destroy everything, even her own best friend's happiness. Willing to do crazy things by doing fake marriages that finally made her fall into a deep hole—which she couldn't explain how deep, but enough to make her feel a sensation of pain when she got to the bottom.