Has your partner ever experienced skin reaction after engaging in sexual activity with you?
If yes, it might be semen allergy.
Read article:
http://www.mnn.com/health/allergies/stories/woman-is-allergic-to-sex-with-husband

Semen Allergy
Has your partner ever experienced skin reaction after engaging in sexual activity with you?
If yes, it might be semen allergy.
Read article:
http://www.mnn.com/health/allergies/stories/woman-is-allergic-to-sex-with-husband