We are sorry to hear of your struggles with OCD and
niddah and we appreciate the sensitive nature of this question.
Generally speaking, if a man finds
blood following relations on anything other than his sexual organ itself or on a towel used to wipe it, the bleeding is assumed to be from another source. Blood found on a
colored towel or
disposable tissue may also be disregarded, as long as the husband did not wipe within seconds of relations.
Stains in the sink are assumed to have been there from before or to be something other than blood. The halacha concerning sheets is as you wrote. A tiny speck of blood within a white stain on a dark sheet would not be problematic, both because it is tiny and because the sheet itself is dark.
Once you’ve washed yourself, nothing you find on your hands, on paper, or on any other surface could possibly be a problem.
Even blood found on the male organ does not necessarily mean that the woman is
niddah, depending on the circumstances. And even if your wife were to become
niddah during relations, this would not be considered a witting transgression. Halacha was made for human beings, not angels, and God is forgiving.
Generally speaking, if your wife is not concerned that there has been bleeding during relations, you should rely on her assessment and assume that your doubts are not of halachic concern.
[The original answer included a referral to an expert local Rabbi with a background in counseling.]
2024: For a more in-depth discussion, please see our article on
OCD and Niddah Observance.
