Semen Allergy

So I have been sexually active for 14 years now and have had more than a handful of partners. I have used numerous methods of birth control as well as no birth control at all. I have finally found my soul mate and the love of my life and we currently use the withdrawal method. I have used this method in past relationships, typically the semen would end up on my stomach. I have never in my life had or seen any reaction on my skin until this relationship. Where ever the semen touches my skin I become red and slightly inflamed. He jokes that I'm allergic to him and after today I'm starting to believe I am. I tried doing some googling but haven't really come up with an answer as to why his semen, in particular, is making my skin react. I read he could have extra proteins or the ph of his semen could be slightly off. I'm concerned that when we decide it's time to conceive the inflammation will be inside as well and that doesn't sound like fun. Can anyone add some light to this topic?