The ending with Gabe meeting and, presumably, falling in love all over again with an alternate version of his wife in an another universe the very same way he did in his: bringing a helpless, injured dog (who'll eventually become theirs) into the vet clinic she worked at.
Gabe: My grandfather taught me the energy of life goes in a circle, in a perfect flow; balanced. He said, until I find my center, my circle would never be whole. That day, I first saw her [TK] in the clinic, I came in with a dog that was hit by a car. I knew right away she was my center.