You and I disagree about whether this is collateral damage, not because we have a different definition of collateral damage, but because we disagree about whether there is intent in this situation.
If the end-goal is to have sex with a woman, and you choose to hurt this woman to gain it, then her being hurt is part of the plan—and is thus intentional. It is an important sub-goal of the main plan, which is what makes it intentional.
You could have instead chosen to buy her flowers, flatter her, or to choose a different woman (one that does not need hurting for you to gain the end-goal of sex). The presence of acceptable alternatives is one reason why I consider this situation to not be a case of mere collateral damage, but of intent.
You are using the word incorrectly. This is independent of what behavior is ethically acceptable.
All damage that is incidental to the primary purpose of an action is collateral damage.
Additional note: Calling Bob collateral damage when you run him over so that you don’t kill lots of children is a correct usage.
You and I disagree about whether this is collateral damage, not because we have a different definition of collateral damage, but because we disagree about whether there is intent in this situation.
If the end-goal is to have sex with a woman, and you choose to hurt this woman to gain it, then her being hurt is part of the plan—and is thus intentional. It is an important sub-goal of the main plan, which is what makes it intentional.
You could have instead chosen to buy her flowers, flatter her, or to choose a different woman (one that does not need hurting for you to gain the end-goal of sex). The presence of acceptable alternatives is one reason why I consider this situation to not be a case of mere collateral damage, but of intent.