Sex denial in Relationship

Note: I will not be disclosing gender in the problem as it can lead to Prejudice. I would like to call partners as "A" and "B" and yes they are Heterosexual couple We have scenario: A & B met in uni and they had lots of sex. During the relationship "A" use to tell "B" about how he would have sex with his/her ex boy/girl friends. "B" was not happy to know "A"'s sex life with his old ex. After a while(4 years) relationship matured and A & B decided to get married. After marriage B started to refuse sex to A and it happened regularly for 10 years(Sometimes no sex for 1 year). Now A has moved out of the house and asking B why sex was denied. B responded by saying because "A" spoke about his sex experience with ex boy/girl friend I refused sex. I think it very unfair on "A" because "B" kniew everything when she married "A" and should have objected then not after marriage and 10 years. Please let me know your thoughts