I’m often asked if it’s OK to end sentences with prepositions. The answer is definitely YES. The injunction against doing so comes originally from a Latin construction, but no reason exists not to end sentences with prepositions in English.
Someone recently asked me, “Would you write, ‘Where is the library at?'” Of course I wouldn’t. I would ask, “Where is the library?” That “at” serves no purpose because the word “where” is already asking for location.
Would you ask, “Who was that person with whom I saw you?” I very much doubt it; instead, you’d rephrase the sentence to say, “Who was that person I saw you with.” As you can see, ending sentences with prepositions often makes sense, sounds more natural, and will keep you from sounding like a grammar pedant.