Technical single (in my opinion) is for people who do not want to be in the relationship.

This is what I am so confused about. I don't see how you can look at a person one day and think, I want to date them exclusively, and the next day they are fucking some random person. I couldn't do it. I couldn't feel like I want to date a person, and when they say, "shit it's a bit fast can you let me think?", I go and ride some other guys dick. I think, what kind of person would that make me? I wouldn't be proud of myself. And so I can't understand why my boyfriend and my sister think it's totally fine to hide what they are doing / have done, because they know it will hurt the other person. In my opinion they shouldn't be doing it in the first place. But both of them have a very selfish streak, and I border on being burdened with empathy.

I couldn't do what she is doing and like myself. I couldn't do what he did and like myself. And so facing it on a regular basis is making me struggle to like them, and I don't know what to do about it.