My friend need help

She live with her bf n they are not ttc. Her period was on d 20th to 23rd june. They had sex on d 25th,29th june and on d 2nd,8th, 12th july. But on d 5th july she had sex with another guy n they did d pull out method. Now she is 5 weeks n 5 days pregnant and she is worried who d father is. The bf just find out she is pregnant and he is really happy. D other guy didn't know. Pls help who do u think might be d father?