Looking for an animated movie that I watched parts of when I was a child, so it would have been from the mid 90's. Possibly may have been created in the early 80's.
Memory's a bit hazy because it was so long ago but it involved a man falling in love with a being (alien?) that had no mouth and a hole where its stomach was meant to be (I could just be imagining that last part) possibly they had a child together (again could be imagining that too)
I do remember there being a woman that got angry that he was more interested in the other species. Also could have been an adult animation because I do remember that I had been watching it late at night.