My girlfriend keeps in touch with her ex-boyfriend and basically talks about QQ every day. I didn't reply to her message. She said I didn't take the initiative to care about her. What should I do?

According to your description, I have come to three possible conclusions:

1, your girlfriend has never forgotten her ex-boyfriend. You are just her body body double when she is empty and lonely.

She compared you two. She prefers her ex-boyfriend, but she is afraid that there will be no successor after her ex-boyfriend rejects her, so she rides a donkey to find a horse. If her ex-boyfriend refuses her, she will follow you, or she will go to him. This is just a metaphor, don't worry.

3. Your question. Or the conditions don't satisfy him, or he is too busy to take care of her, and he may have had a bad time with her recently.

According to your description, the possibility of the third one is extremely low.

The solution to this problem depends entirely on you.

See if you like her enough. If you don't like her very much, you should stop. If you can't live without her, try to get to know her ex-boyfriend and see his attitude first. Know yourself and know yourself, and you will win every battle. You can ask if you don't understand.