There is a passage with some blanks to fill in with proper words.
The passage is mainly about a veterinarian who always felt hard to comfort the pet owners after performing the euthanasia of pets. But once after he again performed one on a dog, a four-year- old boy's words, to his feeling, were really comforting.
Here is the extract of the passage, where I feel confused about the option of two words for a blank.
"...Making this final decision is painful, and I have often felt powerless to comfort the sad owners. But that was ________ I met Shane.(referring to that little boy who later said comforting words）"
A. before B. until
The answer is "before", then isn't "until" right in the sentence? Thanks for your reply!