I don't doubt that she was the prime mover in the Little Athletics involvement. She may have even suggested to him that it was a good way to meet new people. Funny thing is (I was the poster who first mentioned the appearance of his home) whilst I was surprised that his house was so scruffy, I am doubly amazed at its appearance given that his partner also lived there. No sign of a woman's touch (sorry, yes I know its sexist to say such things), but really, be honest with yourself. If someone showed you a picture of that house and asked you if you thought a woman lived there, how many would say yes? The only difference since she moved out is that the lawn hasn't been cut. Maybe she's not all that house proud either? The place never looked any better when she was there.
Sometimes you see someone singing and the face really doesn't match the voice. This house just seems like that. Something just seems off. I'm not suggesting anything, it just doesn't look like the family home of a man who's been gainfully employed for the last thirty years, serial killer or not.