Is it normal to be turned on by the thought of someone else having an orgasm?

I guess it's always turned me on, but it's not until recently I started to notice it. Like if I see a picture/gif of a girl or even, though more rare, a guy who looks like they're having or about to have an orgasm it turns me on. Even during a video, it doesn't matter what's happening if I see actions, faces, or sounds associated with it, it'll get me. Especially during the sexy times with my girl, but that's a little different because there's physical contact, but still. Just wondering if this is normal or would it be classified as a fetish or what?