The title can be taken two ways, both of them true.
Choice #1: Getting herpes is a choice in that having consensual sex is a choice. When consenting adults have sex, we understand the inherent joys and the inherent risks associated with the decision. Many times when people feel hit like a ton of bricks about the herpes diagnosis, it’s because they didn’t fully consider the true risk. Specifically, I was always under the distinct (and cliché) impression that it just won’t happen to me. And once it did happen to me, I immediately took on the victim mentality and shifted the blame to the person who ruined my life (my then-girlfriend had cheated on me, making her an easy target; but it wasn't until years later that I owned that I wasn't truly invested in the relationship way before she cheated). Making ourselves into the victim is a common self-protection mechanism, yet so destructive to our own feelings of personal power.
(Important clarifying note: For those who got herpes through non-consensual ways, your original choice and personal power was taken from you. Choice #2 is where you can take that power back.)
Choice #2: The more important meaning of "herpes as a choice" is how we interpret herpes in our lives. This is the most important decision we can make. Herpes by itself is just a virus, a thing with no inherent good or bad qualities. (Sure, it can create an uncomfortable situation, but so does the flu.) We can choose to have it mean the end of the world or we can make it a catalyst for learning and growth. We can make it an opportunity for authenticity and greater depth of connection. All information comes to us as unprocessed stimuli, raw data … we then assign meaning to it to the data as it comes through our perceptual filters of the world. So ultimately, we are the deciders of our experience. Like Viktor Frankl said, "When we are no longer able to change a situation, we are challenged to change ourselves... Everything can be taken from a person but one thing: the last of the human freedoms—to choose one’s attitude in any given set of circumstances, to choose one’s own way." Our perspective and the meaning we assign to the happenings in our lives determine our experience of them. And that is true power.