Best suggestion I've seen in this thread is pretend you're a guy. If that doesn't work then he's just harassing you for the hell of it. If you sent him pictures or confessed your love for him at some point then you're screwed and will just have to deal with it.

I highly doubt SE considers this harassment, it's just emotes at this point and they don't actually effect you unless you let it. Maybe your best option is to lighten up a little and ignore it.