The first thing we hear about Abhidha is that her name translates to "longing" (4.8). Unsurprisingly, then, she's Hassan's first love and first girlfriend—a.k.a. the first person he longs for.
Abhidha's described as quite smart with a serious intellectual streak. She's also twenty-three and Hassan's… seventeen. It's not quite The Graduate, but their relationship happens right after Hassan loses his Mom, so we think it's safe to say he's working out some mommy issues with this one. He also says that she "was a kind of kindred soul [that] would bring out that driving ambition buried deep inside" (4.11) him. You know who helps foster our ambition? Our moms.