masturbating Vs. Sex

Okay so when me and my boyfriend have sex it feels great and sometimes I'm on the verge of cumming but I don't think I ever have, but I masturabated once just using clitoral stimulation and whoa like it felt like really amazing. Like I felt like I was on cloud ☁️ 9 or something. Like my body just started getting weak . But why don't I feel this way when we do have sex? Can someone explain