Another possibility is that Natsu tries to hide his pain and act like it doesn't matter. He might put on a brave face in front of Lucy and the others in the guild, but deep down, he is really hurt. This could lead to some internal conflict within him as he struggles to deal with his unrequited love.
He may try to understand Lucy's reasons. Natsu is not the type to give up easily, so he might start to work on himself, thinking that if he becomes a better person or a stronger mage, Lucy might change her mind. He could also try to be more patient and give Lucy some space.
Natsu might be initially shocked and sad. He could go off on his own for a while to think about what happened. Since he's a passionate person, the rejection would hit him hard.
He may try to understand Erza's reasons. Natsu, despite his impulsive nature, has a big heart. He might respect Erza's decision and step back, trying to keep their friendship intact. However, he could also be a bit persistent in a non - annoying way. He might keep showing his care for her in a more friendly manner, hoping that over time, she might change her mind.
He might be initially heartbroken. Harry has deep feelings for Hermione, so the rejection could come as a shock. He could withdraw into himself for a while, feeling sad and confused about why she doesn't feel the same way.
Natsu might be initially shocked and confused. He's not the type to expect rejection, so he could be at a loss for words at first. For instance, he might just stand there with his mouth open, not believing what he just heard.
Well, Natsu is a passionate character. He could react with a lot of excitement. He might pick Lucy up and spin her around, laughing and saying how amazing this is. Or, he could also get a bit worried and start asking Lucy all sorts of questions about her health and what they need to do next.
Perhaps he tries to convince her. Harry is a determined person. He might think that Hermione just needs more time or that he didn't present his case well enough. So, he could start listing all the reasons why they would be good together, from their shared history to their mutual understanding of the wizarding world. But if Hermione remains firm in her decision, he may finally have to accept the rejection and move on.
One possible reason could be that Lucy is too focused on her own goals, like becoming a stronger mage or achieving something specific in the guild. She might see a romantic relationship as a distraction at that moment.
Natsu would likely be extremely guilty. He might immediately stop whatever he was doing and rush to Lucy's side.
He might be initially shocked. Natsu is a character full of energy and sometimes a bit clueless. So he could be stunned into silence for a moment before breaking into a huge grin, excited about starting a family with Lucy.
Their love often develops through shared experiences. As they go on adventures together, they start to rely on one another more and more. They see each other's strengths and weaknesses and gradually fall in love.
Their friends would likely be shocked at first. Happy for them, but also a bit worried. Erza, for example, would probably be very protective. She might start giving Lucy all sorts of advice on staying healthy and safe during the pregnancy. Gray might be a bit awkward around the whole situation at first, but would eventually warm up and offer his support in his own way, like helping Natsu with any odd jobs or tasks so he can focus on Lucy.