Questions: Girl's Behavior

I mean, what if the girl used to be very chatty and interested, and now she leaves you on read? I'm not sure if I've somehow hurt the girl or if she is genuinely busy (like she claimed to be). Like ok, maybe she didn't feel the need to reply to my text (which didn't necessarily require a response)? But still, it's a bit rude.

When she replies, should I give her the same treatment (if her message doesn't necessarily require a response)? I still care about her, but I hate that she left me on read twice in a few days (not twice in a row, but still). I just don't want to loser her either.

I always get these blank faces and then they quickly look away. It’s as if they are looking at me trying to determine if they know me but the thing is that I feel them staring at me so I look at them, we make eye contact and they look away. Some smile a bit.

What does that mean? Girls do this to all guys? It means nothing at all? I can’t even make a poll because I have no idea. I pasted below the exact faces they are making when we make eye contact.