Title VII only controls employers in the context of employment. The employment context can include activities away from the employer's premises. However, the activity has to be related to the employer-employee relationship. For example, activity conducted while on business related travel, social activities sponsored by the employer, business meetings away from the employer's premises are in the context of employment. However, if employee A engages in unwelcome conduct of a sexual nature to employee B in a bar where the two of them just happen to encounter each other or as the result of a meeting they arranged, but which has nothing to do with the employer or its business, the sexually harassing behavior wouldn't be illegal because there is no employer-employee relationship between employee A and employee B. For Title VII purposes they are just two individuals "passing in the night."
Under Title VII an employer has the obligation to ensure a workplace free of conduct that violates the law. Two individuals who happen to work for the same company meeting or being in the same place doesn't create a workplace for which the employer is responsible.