This is a difficult question to answer, because the usage is changing. "She's the one whom I loved" is "correct," but it will sound slightly irritating to some people, to whom :) it may seem formal, pedantic, and old-fashioned. "She's the one who I loved" is widely accepted, but it is irritating to the ear of older and more educated listeners because it isn't quite correct. The American Heritage Dictionary's usage note about this is 485 words long! You can find it at https://ahdictionary.com/word/search.html?q=who In my opinion, the best solution to many such problems is to sidestep the issue entirely. Rewrite the sentence so that you don't need to use either form. In this case, you don't actually need the word "who" or "whom" at all. "She's the one I loved when I was young" is fine. Similarly, you can say "He’s the one I met last year." I don't understand the meaning of "He’s the one who framed me in the company last year." However, there is no usage problem here. "Who" is the subject, so "who" is correct. Notice that the sentences are saying, respectively, "I loved her," "He framed me," and "I met him." One final thought. If you are answering questions on an English exam, then you need to be careful. Otherwise, when in doubt, the safe choice is "who." The reason is that using the pronoun "who" for a direct or indirect object is only a small mistake, is very common, and some would say it is not a mistake at all. On the other hand, using "whom" for a subject sounds awful. It's "hypercorrection." It sounds as if you are trying to be an expert when you are not. Don't use "whom" unless you are really sure it is correct.