Must your SO know if you plan to have an abortion they won't approve of?

You, as a 21 year old female, discover you are pregnant, even after being very adamant and strict with birth control. You have been in a loving relationship for 5 years and have an amazing relationship, but you do not want children, especially not right now. You are about to finish college, get married, and do not want a child. You didn't have a particularly great childhood, and you want to experience life, and life with your SO. You are torn on whether or not to have an abortion because you know how it would affect your relationship if you brought it up, and especially if he knew you were considering something he doesn't agree with. But, you are considering proceeding with the abortion discreetly. You know that hiding it will only make it worse if the situation came to light, but if you sought his acceptance, it would not be given, and your relationship would either be strained by 1. carrying an unwanted pregnancy (considering the implications on the child if born to a mother who isn't thrilled about being a mother so soon) 2. him knowing you wanted to abort and/or 3. proceeding with the abortion, despite his wishes. Adoption is not an option because he would not agree to it, and you would consequently be raising the child anyways, unless you split up, but then there is a child who will grow up without one parent.