Does it mean they are just busy or just doesn’t want to reply to you if they often disappear in the middle of a conversation?

Not about romance.
An acquaintance not even friend, always disappears in the middle of the conversation, they are always the one that initiate conversation, and when I answer their questions, they just go no response, sometimes reply days later and sometimes never. They did it for multiple times. I was kinda upset because I think it would be disrespectful to do that, especially when I ask them questions and they go silent.
These days they kindly reached out and was nice so I just responded kindly and they did it again. I then sent them a “?”, they just said they were busy. But I saw their messages in a group chat. Then they asked me a lot of questions to show interest.
I just hate when people do this, they start a conversation, I open up and tell them about what’s going on lately in life and they disappear.. they claim that they want me to join their friend group but from the conversation pattern, I think they don’t have a genuine interest?
Does it mean they are just busy or just doesn’t want to reply to you if they often disappear in the middle of a conversation?
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