Welcome to the Wefugees Community and thank you for reaching out to us. @Poji1234 is right in mentioning that your residence permit is not necessarily dependent on your girlfriend but on your child instead. It will be important that you keep caring for your child and see it regularly. I hope you and the child's mother can both cooperate and act in the child's interest.
So, it is possible to get the extension of the residence permit, but it might be a bit harder to prove that you are still caring for the child and take an important role in its life. At the end it is at the disretion of the immigration office.
Would you agree dear @manrhei-mbeon or @mbeon-Rukundo and is there any advice you could give?
Please also don't hesiatate to get back to us with any further questions.
All the best,