You might start a conversation with her about the story. For example, ask her what she liked about it. This can help you get to know her better and also show that you value her opinion.
First, don't overthink it too much. It's a great feeling when someone likes your story. Maybe you can share more of your stories with her if you have any. If you feel comfortable, you can also ask for her thoughts or feedback on your story. This can not only help you improve your writing but also strengthen your connection with her.
In many platforms, you can see who liked your story. Usually, there's a feature or section that shows the list of likes and the names of the people who liked it.
It varies. On some platforms, others can see who liked your story, but on others, this is kept confidential for privacy reasons. Usually, the platform's settings or terms of use will clarify this.
It's hard to say without more context. She could be anyone from a friend who took over a conversation you were having about a story, to a classmate who maybe used your story idea for her own work.
I recommend the following two novels to you. Both of them describe the plot of many men liking the same woman ~
1. "Hello, Prince": A girl dressed as a man was liked by many men, including her brother's former "arch-enemy." The interaction between the male and female leads was also very sweet.
2. <Honey Jelly>: After the female protagonist was regarded as a viper by her husband, she found out that there was a princess in her husband's heart and a mistress came to apologize. In the end, the female protagonist successfully counterattacked, bid farewell to the mistress, and won the love of the CEO's husband. I hope you like my recommendation. Muah ~