Why do some women seem to think that if you aren’t dating a guy exclusively then he doesn’t owe you the truth especially when a guy is in a relationship or has kids and lies about it ?

I recently started dating ( past 6 months ) and I’ve caught guys in some lies and some people have made it seem like if you aren’t exclusive with the guy then you can’t confront them about anything basically trying to say he doesn’t owe you the truth

This guy recently lied to me about having a child on the way and a girlfriend ( today ) and some females made it seem like I couldn’t question him or confront him because we weren’t officially together which made no sense to me. I’m not about to wait until I’m in a relationship with someone to be made a fool of . What’s so hard about keeping it real?

Thoughts? What do you think about these types of women or men