Because he was not just her lover, but also the father of the baby in her belly.
She gently stroked her belly, thinking for several days, and in the end, she couldn't bear to give up this child.
During these four years, she took care of Tommy. Sometimes, she couldn't help but think of the child she gave up before. Although it was an ectopic pregnancy, she knew in her heart that even if it were a normal child, she would still give it up five years ago.
She planned to explain everything to him by herself; whether he could accept it or not was his problem.
She also understood that most people would have difficulty accepting their girlfriend suddenly becoming an "unwed mother." Even if the child wasn't hers, many would not understand.
In any case, if Robert Thomson could accept it, everyone would be delighted. If he couldn't... then she could only apologize. She was a mother first and his lover second. She wouldn't give up Tommy. So, she had to let go of him.
