hey takniteasy;
ask your s/o to show you how/where etc he found 'his' porn. tell him you are turned on by it and want to find some of your own.
that way you get a little bit of 'together porn' while he is showing you want to do (in terms of finding it on the net). you can also play dumb after you find some and have him show you how to view it etc. this way you can gradually get some more 'together porn'
by doing it this way he may feel less intimidated by you being with him. eventually you'll be watching it together all the time.
i don't think it is a private thing, i think he is more than likely a bit embarrassed by his viewing habits.