My experience with a girlfriends dog was a little different to some of the comments , before we had any sexual interaction he was a little wary and slightly aggressive towards me if i was alone with him but manageable, after a few experimental interactions and him actually fucking me he started to become more aggressive and assertive towards me, it was quite intimidating when on my own to the point he started to scatre me when he wanted to interact by sticking his nose where it shouldn't be more so just before my period started, while with my gf he would look at me but behave, I think he started to think I was his any time he wanted, I got to the point i couldnt be outside with him if she wasn't there, he continually tried to mount me and start to become more assertive the more i tried to resist him, he was worse than some of my ex boyfriends.