Why would someone bleed after everytime they have sex?

? Trauma: If partner is too big may sustain micro tears causing bleeding or infections may cause bleeding. Get checked.

Cervical trauma?: Light bleeding after sex is quite common for those having a male partner who is a bit on the long-side--repetitious trauma of the penis pushing/thrushing on the cervix which can bleed a bit. If u have some cervical polyps, fibroids, infections, cancer, bleeding is even more common. Seemingly this of some concern to you, i would advise checking it out by your doc. Good luck.