Could ejaculating oftenly causes acne on the face?

No: There's no connection, beyond the fact that both are characteristic of most male teens. Enjoying your body in private won't harm your health; vary your technique, and think of something nice -- maybe the girl you'll marry -- rather than internet trash. If topical benzoyl peroxide doesn't clear your face in two weeks, get with your physician for prescription-strength rx. Enjoy who you are.