I took college level French in the sixties. Having grown up twelve miles from the Mexican border, taking Spanish classes in Junior and Senior High School, and having an exchange student from South America living with me meant my Spanish was pretty good. At the University Spanish was not suggested for my major’s language requirement, so I shifted to French.
They speak of how knowing one Romance Language makes all the others easier. In some ways I expect that’s true. But no one warns you that learning similar languages can screw up your knowledge of both languages. To this day I inter-mix French words with Spanish words and sometimes throw in an English word when I’m really frustrated.