There are some universal truths in the world, and as much as we'd like, nothing we can do will change them. Peanut butter has fat. It is, quite simply, peanuts ground into a butter. You can roast the peanuts, you can add salt, and if you like it less thick you can add peanut oil. If you use anything else, you aren't making reduced fat peanut butter, you're just making less peanut butter.
Most commercial peanut butters have a lot more ingredients than peanuts and salt. Reduced fat peanut butter has even more. But while reduced fat Skippy has 6 grams of fat per tablespoon, as opposed to 8 in regular (which is still loaded with crap), it also has more sugar and more sodium. You're trading natural, real flavor for the illusion of health.
Fat will always taste good, and it will always have fat in it. It is why you fell in love with peanut butter in the first place. It is the moody, complex artist you went after, then dated, then got upset with for being moody and complex. It's time to embrace reality. Start with peanut butter.