You have an incredible disconnect between what you want and what you are doing. This is the second or third thread you have started about the same topic in the past couple of months. Clearly something you are doing is not working out.
I'll do the math for you:
The reason this isn't working out is because you want your cake and to eat it too. What you are doing isn't friendship. It isn't honesty. He thinks one ruleset is being used and you want to change that ruleset to something else without telling him. At the same time you are still dating other people. So I can't tell if you are actually serious about this guy or if you want it where he isn't dating other people but you are. Either way your actions need to match what you say and what you want.
There isn't some magical fruit you can eat that suddenly whisks your emotions away. You aren't built that way. I think you would be a much healthier and happier person if you concentrated on who and what you are, not what you aren't. If you are an INFP, we usually move to the beat of our own drummer in life. Figure out what music she is playing.These feelings of jealousy are surely some knee-jerk response in me that I can overcome so I can just enjoy the relationship as it is. What are some suggestions?
And one last note on NTs and emotions.... they are for the most part better at keeping their emotions in check and concealed. It doesn't mean that they don't have emotions or that they aren't affected by emotions.
And in regards to why your INTP is content, it's pretty simple. He's a guy who gets a no strings attached sex relationship with someone with whom he doesn't have anything official going on so he doesn't have to deal with the messiness of a real relationship. (Ie, "Can you do the dishes tonight?" "Honey, I had a bad day!" "What do you mean your plan for tonight is to sit in your underwear, drinking beer, and watching golf for 8 hours?!" etc)
End of the day:
Be honest with him. Tell him you want something more, something exclusive, and something just with him. Let the ball be in his court for a bit to decide.