Why does my pussy get so wet when I'm getting fucked in the ass?

It was my idea to have anal sex, because for inexplicable reasons I currently really like being fucked in my MILF ass. I even had two orgasms quite quickly. However, in my opinion, those are not the most interesting facts in this video. Rather, it's the fact that my sweetheart got really horny when, in addition to his cock in my backdoor, I also started fingering my cunt. It really turned him on that I was massaging his stiff dick through my pussy while he was pleasuring himself in my tightest hole. In order to be able to cum, my husband even ended up playing in my wet slit, and now I'm no longer sure whether it was my asshole that drained him or whether it was the stimulation of my very wet pussy.