1. She genuinely likes the poem: She might be expressing her appreciation for your effort and thoughtfulness in creating something special for her. "Sweet" can be a positive and endearing way to describe something that is pleasing or charming.
2. She's being polite: It's also possible that she's simply being polite and doesn't want to hurt your feelings. She may not be overly enthusiastic about the poem, but saying "that's sweet" is a gentle way of acknowledging your effort without overcommitting to her reaction.
3. She's not interested: While it's rare, there's a chance she might not be interested in you or the poem itself. In this case, her response may be a polite way to let you down easy.
4. She's unsure about her feelings: Sometimes, people may use the word "sweet" when they're feeling a bit uncertain or unsure about their own emotions. It could be that she's unsure about how she feels about you or the poem and is choosing to give a safe response.
It's important to consider the context and tone of her response to gain a better understanding of her feelings. If you're uncertain about her true meaning, you could try asking follow-up questions or initiating a conversation about the poem to get a better sense of her thoughts and emotions.