You got it right when you said you will have to trust her to make the right decisions about her sexuality.
You also got it right when you noted that romance novels can breed sexual interests in young people.
Her statement, "I almost feel immature for thinking it's wierd because people have sex all the time" is a tacit reflection that her views about sex have changed somewhat over the last few years.
It is almost certain that some years back she would have been appalled at how easily other girls gave away their virginity.
But wait. What is the problem with romance novels?
Whether the readers admit it or not, romance novels breed feelings of curiosity among young virgin girls and boys.
They have never experienced what sex is like. The romance novels tell them it's fun, it's exciting, it's worth giving a shot at.
Parents don't want to discuss sex . . . they feel embarrassed if the subject comes up for discussion.
The only 'credible' source of advice would seem to be romance novels, at least for the young readers.
The friends in school also seem to corroborate the fun part of sexual activity described in the romance novels.
When you see young girls in groups chatting away about the weekend party they had, it's almost certain that romance and sex would feature as exciting subjects.
This two factors - romance novels and sexually active friends - will not make a decent girl fall to immorality automatically.
It takes time.
Continued exposure to sexual and romantic scenes in books or movies weaken a person's ability to resist when a compromising situation arise.
Think about it.
What happens to a girl or boy who is deeply spiritual and voraciously reads any spiritual book in sight?
He or she becomes spiritually strong and active. And overcome temptations more easily.
Conversely, what would happen to someone who is repeatedly exposed to romantic scenes?
Your guess is as good as mine.
Should you be worried?
No. But I think you should be concerned.
What can you do?
Have a straight talk with her. Tell her you have noted with interest how she enjoys reading these romance novels.
Tell her you want to join her in reading this stuff. But first, you will like to know what you stand to gain.
You can't make her stop reading unless she wants to. But you can help her see that continuing in this course may be unprofitable in the long run.