Radar Online is claiming that Jennifer Aniston and Justin Theroux separated because she kept stalling their plans to have children. “Jen never felt completely comfortable with Justin being the father to her children,” a source says. “She wants her baby daddy to be the perfect man–and in her mind, that’s Brad She wants her child to be just like Brad–in not just looks, but also the personality and charm that won her over 20 years ago!” Aniston allegedly leaned heavily on Pitt in the final months of her marriage and decided she wanted him to be her sperm donor. “Jen didn’t have to ask Brad twice,” the insider adds. “He loves kids, and would be happy to have more–especially with Jen.” Pitt already has six children with his ex-wife Angelina Jolie.