For me what it comes down to is being able to live my life openly and freely. Being someone's dirty little secret just doesn't appeal to me. I find it hard to imagine that anyone in a DADT is going to feel comfortable strolling through the mall holding hands, and that's something I enjoy doing with my partners. If I was walking around with a partner, and they spot a friend or coworker and suddenly drop my arm and put 3 feet between us just to avoid suspicion, I would feel like they see me as cheap and disposable. I am not disposable and I choose not to be with anyone who sees me that way.
The other reality is that when you're dating a DADT, you get zero rights in the relationship. The primary gets first dibs on everything, and you get the leftover scraps. Thanks but no thanks.
I honestly don't care about whose responsibility it is to make sure no one's cheating. It's about my own needs within a relationship, one of which is a need to feel valued and cherished. If someone can't give me that, then I don't need to waste my time with them.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker