Review the item:
When Minori left Japan to study in the United States, she thought that she
would miss her mother's delicious cooking, however, after her first taste
of a bacon cheeseburger, she did not care if
she ever returned home.
She did not care is a main clause. If she ever returned home is a subordinate clause. A subordinate clause is an incomplete thought which you must attach to a main clause. When a subordinate clause follows a main clause, you generally need no punctuation between the two.