I am blessed with a small penis and have been taking small steps with my wife towards SPH. 
At first it was just talking about it - she wasn’t convinced I was particularly small - but using g a ruler and showing her the charts you can find on the internet have convinced here that 3 1/2 inches hard really is SMALL!

With my encouragement she will now talk of previous boyfriends and their size and compare them to me.

We have started a bit of role play in the bedroom where she is visiting a masseur. It is a great way to encourage her to talk about me in the third person and to my great delight she will talk to “him” about me “he has a tiny penis like a little boy’s”. Needless to say I love it. She still thinks it’s a bit crazy but is happy to play along with my little kink.

I would love to take this further and actually get to cuckolding. I would love to see her having sex with her guy with a big cock but at the moment I think this is a long way down the line.