How can you tell when you've fallen out of love with someone?

So I never even dated this guy, but we had a thing once and I've loved him ever since, for the last three and a half years. But I don't live near him anymore, and I tried dating someone else to get over his (as bad as that might sound I guess), but it made me feel guilty, like as if I was cheating on my own heart if that even makes sense. But I don't think about him much anymore, and other guys are seeming to become more attractive to me, yet I still compare their personality to his (he's by far, one of the best people I've ever met). Idk if I really have stopped loving him, or if it just seems more distant than anything. What do you think?