My oldest daughter is a lesbian. If she was ever molested she has never mentioned it to me. The only “abuse” she suffered was the fact that her real father didn’t bother much with her or her sister after our divorce. Their stepfather was a far better father to them. Her three sisters are all straight.
Interesting enough her partner’s parents are also divorced, and her father is absent in her life.
I don’t think we can make blanket assumptions about abuse or molestation.
I do think a lot of homosexuals experience some sort of trauma, but it isn’t all necessarily abuse. One study showed that lesbians lost their mothers (to death) in the preteen years at a much higher rate than the general population.
Think of the women who are married for 15, 20, 30 years and are divorced and now “out.” I think the trauma from the divorce is a driver.
I think there are definite self image problems and I think the psychological community really needs to study these and help people deal with them.
For some divorce alone is enough.
I certainly don't know if this is the case with your daughter, but a sensitive person might sub-consciously lose all hope of a man being committed to her if she sees such a dynamic happen with her parents.
That's not something that people just "mention" in a matter-of-fact sort of way. Even if you are close to your daughter, it would be difficult to talk about, especially if it was a family member or a close family friend.