I dont feel any sensation while doing sex.

It’s been a year, since me and my partner got physical. She is really beautiful and hot. Every time we get to intimacy i get turned on by her. But the problem is when ever we try penetrative sex, i dont feel any sensation on my penis. This problem is from day one. Eventhough i dont feel any sensation but i stil cum inside here and the orgasm is also good. But why is it that i dont feel any sensation on my penis. Can someone help or guide me?