Why is he doing this?

Themba is a changed man towards the mother of his children. Themba has a lot on hit plate, he has a wife now and he is expecting a third child with Mpho. On the other hand, the mother of his children wants him to help her to move to another place but he refused.

 
He told the mother of his children that she is not his responsibility, but his children are. The mother of his children Nqobile was hurt to the core. Themba cannot say this to a person who have been supportive and taking care of him for 9 years.

It looks like he wants to take care of Mpho because now she is part of his family. Themba is known for his good heart but now he is showing his true colors. He makes Nqobile to sound desperate but she is not.