Fear of retaliation from the molester, fear of not being believed by the rest of the family, or even possibly blamed. When I worked in the shelters women told me about actually having been blamed by their MOTHERS as children because their fathers, stepfathers, uncles or brothers were molesting them. Unbelievable.
Fear of retaliation against them or others (possibly blackmail or threats of harm)
Fear of not being believed by those she told
Fear they will be devalued in the eyes of everyone (no one will love her if they found out)
Feelings of filth
Feelings of insignificance
Guilt for enjoying, or being told they are enjoying some aspect of it. ("it's not rape because you're loving it" kinda thing)
Gotta make her feel safe. Feel loved. Feel cared for. Gotta make sure those she is trying to protect are also made safe and cared for (siblings and parents are a big one here)
Fear, embarrassment, victim-blaming, anxiety, stress, feelings of worthlessness. There's actually a lot of reasons depending on the girl and the situation.
Shame or embarrassment. Denial. A sense that it is his/her fault somehow. The desire to keep the family member from getting into trouble or to prevent other members in the family from being hurt. In some unusual cases, actual enjoyment or a feeling of "connection" or bonding with the abuser.
It is not an easy thing to talk about. Then you have the issue of trust, being will they actually believe you about it?
She's scared!? She's afraid people won't believe her!?
Fear that nobody will believe her or they will tell her not to say anything to anyone leaving her as a victim
none, talk about it to multiple trusted people, I would hope they would take your side. There is power in numbers
Afraid no one will believe her, feels shame.
Because of the fear of not being believed. The molester has said that he/she will be the one blamed and parents or whomever they tell will be angry with them. Telling them they are disgusting and dirty.
Fear of consequences
Believes she wouldn't be believed
Feeling trapped and helpless
fear of retaliation, no one believing.