An open, honest relationship doesn't include digging into somebody's past without discussing it in advance. Feeling entitled to everybody's (potentially private) background details and digging at it rather than discussing it with them first? That's also not very open and honest.
I can respect that you and some others may have been burned, but somebody doing that to me would throw up red flags all over the field, and I'd do us both a favor and simply cut them out of my life at that point. If you ask me about myself, I may very well tell you a great deal, much of which can't be found through other channels, because there's very little I keep hidden (but there surely are some things). I won't generally bother with lying, because I don't have the energy to waste on trying to keep that shit straight.
But if you automatically can't believe something I've told you without trying to do a background check? Then I could never trust you. You've no respect for privacy or personal boundaries. It is toxic behavior. Just because you feel it's justified doesn't make it right.
If you and I were getting to know each other and you asked how I'd feel about you running a background check? I'd probably tell I think it's creepy, but as long as you're footing the bill for it I really don't give a shit. Informed consent is a very important thing.
I can respect that opinion. Open communication is always best. It just isn't reality.
Everybody lies. Everybody. I work in a profession where I deal with this every day, with every single person. People who should be honest when they are with me, but they just aren't. No judgment from me. People hide things for a lot of reasons. To them, they are good reasons.
If you apply for a decent job, there will be a background check. If you apply for a decent job that requires specific privileges, there will be a lot more than a background check. And that is just to WORK. Not be in someone's bed!
For you, Valerie was out of line. You would cut from the beginning. That's fine. For you. That does not make it toxic.
The fact that they shared the truth with each other when the "thing" became more than just a "fling" is the key piece of information here. Again, the MC had the chance to tell her to fuck off. She could have bailed as soon as she learned he was truly lying. But they chose to stick it out and communicate with each other.
For you, this would be that red flag and you would've bailed.
For you. But for them, this was an acceptable path in their relationship. This story is about them,
not you.
Like I said, I can completely respect that as a deal breaker for you. It is good to know your boundaries. We are discussing what happened in a story. While there has to be some suspension of reality in any story, it is realistic to believe what happened in their story. And it is fitting to buy into how they accepted and dealt with the situation.
Like your stance with Z, her behavior crosses a line that puts her into the red flag zone for you. Personally, I am not into dominating women. I would not stand for much of her behavior. But it is far from "toxic" as far as we can see in the story. Red flag? Sure. "Toxic?" No. That is my rub here. That these behaviors are considered "toxic."
Now, combine these single behaviors with other behaviors, other actions, and other scenarios (none of which exist in this story), and you could argue that we've reached a toxic level. One man's "toxic" is another man's fetish!
You, like me, probably did not choose to go down the Z path. It's all good! That is the beauty of a well-written, choices matter visual novel. Don't like that path? You don't have to go down it. But I completely support that those behaviors are red flags for you.