Questions: Girl's Behavior

So i have this girl that I’ve known since elementary school. She’s a nice, bubbly, outgoing girl. Who has always been fit and attractive. In high school and college she started posting pictures of her wearing scantily clad clothing. Now i know that a lot of girls do that and high school / college is kind of a wild time. Fast forward and she’s been married for a few years. Yet she still posts pictures of this nature. Do you guys think that is wrong? What are your opinions on the matter?

picture is not of her

TLDR; girl I was talking to online removed me for no reason, and I don't know why she did it

I met a girl online on this app, on Wednesday. She had commented on a question I had asked once in my local language, and I immediate realized her to be from the same country I was, so we took it to the DMs and hit it off. She gave me her Snapchat and told me she'll be talking to me from there from now on as she was deactivating her G@G account, so we exchanged IDs.

We were mostly just talking and casual flirting, and her responses to all my advances were very positive. She was much more talkative than I was and it genuinely felt like she was actually interested in me and that things may go somewhere if all goes well. I learned that we had a lot in common and that she also lived in my city, just a couple minutes away from where I live.

We'd mostly talk at night because she'd said she had a night job and she'd get free by 12AM. I was mostly awake during the time and I have work to do of my own, so it was fine by me. Last night, I hopped on Snapchat as usual and I saw she had seen my snap but not responded to it. Then I clicked our chat open and saw that she had removed me as a friend.

I really don't understand what happened and why she'd do something like this for no reason. On the night before yesterday, everything was going so smoothly. We talked till 3:30 and we wished each other a good night and went to bed, so this doesn't make any sense why she'd do something like that. Am I missing something? I would appreciate every single helpful response under here.

I had a friend, back in the day. Who once told me she had a collection of naked selfies of herself on her phone. When i asked her why. She said she had them so she could look at them when she felt self conscious of her body. She also said she had them just in case a guy asked her.

I asked another friend sometime later. If she thought that was normal. She said she had a collection of topless pictures for those exact same reasons. Do girls usually have naked pictures of themselves on their phones? Have you ever done that? Is that normal?

The picture for this question is neither of them