So I’ve recently just become sexually active and am wondering if it’s normal to not tell when I’m cumming?

I can feel when I’m close but then it just goes away. He doesn’t stop or anything it just stops? And he is great at knowing how to pleasure me, he’s amazing but I don’t know why I can’t do it. I don’t even know what it would really feel like because it’s so different when I do it myself. Please let me know if I’m doing something wrong or what. Thank you.