Why didn‘t she tell me she was a single mother ?

Me and this women We dated 5 months but for some reason she never once told me that she had a kid. I do respect and understand women who don’t want to introduce their kids to their new boyfriend early on. I‘m aware of the motives of certain single mothers which is why I find it near impossible to date them. I had to end up finding out through my friends that she had a daughter which I think she was trying to hide this from me. There was something kind of funny about the way she was acting and I think this was probably it. What really put me off is that there was obviously a reason why she hid that from me for 5 months which made me think she was up to something e.g. was going to trap me emotionally early on and try to use me to benefit her daughter. When I found this out I backed off and I realised that she started getting frustrated and acting desperate with me which me wonder if she is getting angry and become desperate because I’m not falling for her motive or was it something else? She doesn’t realise that I know she has a daughter. The fact that she hid that from me put me off greatly and I don’t think she knows that I’ve completely lost interest. It wasn’t my intention to offend any single mothers so try accept my apology if I have.