Mentally handicap dating
If the guy is decent then he should have no problem with that...
Someone, like the mother or responsible sister, would have to step in and keep an ongoing dialog with the two regarding their sexual life.
but like shakran wrote, there is just something not right with the way he describes her.
She may be mentally retarded but they way he describes her it seems almost as if he subconsciously despises her for it.
Religion is answers that may never be questioned.." - "Religions take everything that your DNA naturally wants to do to survive and pro-create and makes it wrong." - "There is only one absolute truth and that is that there is only one absolute truth." A decent person, yes of course but it's a tricky situation no matter what IMO.
The whole deal with if the person in question is capable enough to make informed decisions in sexual matters would have to be decided on a case by case basis.