Doesn’t respond to texts..annoyed

I am currently staying at home with my two toddlers. I have a few close friends that I talk to on a regular basis. One of them is a new sahm that I met when our kids were babies and we used to get together all the time. This summer has just been busy for the both of us and we haven’t gotten together much. I am getting super annoyed with her because she will initiate conversation over text and then just stop texting me. Sometimes she will even leave me on read when I ask a question. Sometimes I will text her inviting her to do something and zero response. Today I texted her this morning to ask if she wanted to get together with the kids..no response. A few hours later I saw her Instagram story. So she’s been on social media. It really bothers me and I find it just plain rude. I don’t understand people that don’t text back. I can understand every once in awhile but she does it constantly but then expects me to text back. It frustrating. Is this rude or am I being too sensitive? I don’t understand when people don’t text back. The excuse for her is always she didn’t have her phone- but that’s a lie right? If she’s on social media posting pics? I don’t get it.