Re: My girlfriend does have pain when I ejaculated into her.

You should both be tested for all the stds if you have been monogamous for at least 6-8 weeks.
She could be allergic to you too. Try using a condom to see if it changes anything. It could also be P.I.D. or cancer. She should really get a full check up. Its not normal to always get infections like that if you are healthy.Being on birth control can add to it being an issue. Also not rinsing/showing (and urination) right after sex can make you prone to bacterial infections.