I know exactly where mine's stems from, my mum is also mildly emetophobic so it has been a "learned" phobia.

Same here- I'm a former self injurer and also feel as if emetophobia saved me from going down roads such as drug addiction and alcoholism.

That makes no sense whatsoever- even most non-emets with a brain wouldn't do that! Exposing yourself to things such as eating out etc is fair enough, but doing something that is highly likely to...

You absolutely need to discuss your phobia with him- maybe printing out some info about emetophobia from online for him to read will be useful for helping him understand it better.