Some shippers said something along the lines of "if only Natsu wasn't there"
Why? Mainly because they want to hype other characters as "love interests" for Lucy, but have enough awareness to realize Lucy's bond with Natsu is a cut above the rest. So, the best way these shippers find to hype a premise that contradicts the story, characterization, and NaLu, is to remove Natsu out of the equation.
But, is Natsu truly the only obstacle for other characters to get as close as he is to Lucy?
Let us look at some key moments to find out if Natsu's absence would make a real difference.
First moment we're going to consider is taken from the sequel...
...while both Gray and Erza are quick to join Natsu's attack on the water dragon god, Lucy is the only one who noticed something was wrong with Natsu and his behavior after he got his new power-up. Seeing Natsu's character change, while Gray and Erza didn't even notice, shows us how she has a remarkable understanding of Natsu's personality, which proves how close she got to him, how much she focuses on him, and how he can have a notable effect on Lucy
Was Natsu taking attention Lucy would give to other character if he didn't exist there? Context says otherwise, because none of the characters present did something that could affect Lucy in the same way Natsu did.
Now, let's go way back to the post-Tartaros plot...
...do you remember Lucy's insecurities about the future of their disbanded guild. Who dragged her along to reunite Fairy Tail? Who kept her doubts at bay by constantly reassuring they'll get the guild back together? It was Natsu
But, how would've this played out if Natsu didn't exist? Was Natsu being an obstacle for another potential love interest? Lucy would track her guildmates, but before getting hope from Natsu's impetus, she didn't try to seek them out herself. And none of her guildmates motivated her to take the trip to find them. Only Natsu could give her the push she needed to go on that journey.
We go back to the Grand Magic Games, and we find two moments I'd like to highlight...
...this one is pretty straightforward. A display of emotional chemistry in which Natsu comforts Future Lucy. She felt so insecure that she doubted people would take her words seriously, but Natsu reassured her that no matter what they would believe in her, and went the extra mile to give her the relief and support that she neeeded so much
Now, how would've this played out if Natsu wasn't there? Was he being an obstacle for someone else to have that moment with Future Lucy? This one is a little difficult, some shippers may argue there are guys who have a "spark" with Lucy who could reassure her too. And other more reasonable fans would say Mira or Wendy could tell Lucy they believe her words. But, the guys hyped up by shippers and Mira/Wendy wouldn't have the same potent effect on Lucy. How do we know this?
Recall when Natsu was about to stomp two Dragon Slayers for what their "comrade" did to Lucy. Pay attention to who's among the crowd watching, and how she reacts...
...Natsu is the one who prompts the emotional response highligthed by the manga. So, narratively speaking, Future Lucy is going to respond strongly to the person she watched in that moment. Did the manga highlighted such a response to any of the "love interests" shippers overhype? No, her chemistry with Natsu is part of the reason why that moment is so memorable
The other GMG scene we'll mention is the aftermath of Lucy Vs. Flare...
...right after Lucy breaks down in the middle of the field, the only one who approached her and gave her both comfort and encourage her was Natsu. Another display of emotional chemistry, a partner providing with emotional support when needed.
Was Natsu taking another character's spotlight in this scene? Would someone with a "spark" with Lucy be there to pull this off?
There's no manga evidence suggesting that would be the case. Natsu wasn't being an obstacle, the scene played out in this way because that's the relationship he has with Lucy. Claiming that other character could replicate this moment, and the consistent bonding that serves as a foundation for it, it would be like saying "I want NaLu, but slap the face of my favorite character in Natsu's during their moments"
That would prove NaLu is unmatched in this scene, and the only way other premises have to keep up is do exactly what NaLu pulled off in this moment
Before this post becomes too long, I'll bring up one last moment...
...those who know me probably saw this coming. Lucy was excited to see the rainbow cherry blossom trees, but got sick at the time of the festival so she couldn't go a see it. We then see a contrast between all of her guildmates having a good time and Natsu, who was the most affected by Lucy's situation. And we all know what he did to make Lucy happy.
I don't think we need to ask if Natsu prevented someone else from comforting Lucy and drawing closer to her; because we get a pretty clear panel of most of the guild partying without worries, while Natsu doesn't stop thinking about Lucy.
If we were to remove him we wouldn't have another guy having a "spark" with Lucy, or someone else comforting her. It was always meant to be Natsu
There are many other moments, and I'm sure some NaLu fans out there can point them out, but that's all I'm going to bring for now. And now, a little bonus before going to the conclusion: if Natsu wasn't there in the first chapter, Lucy wouldn't be in Fairy Tail.
Shippers may say Lucy has a "spark" with someone else, and Natsu is the obstacle that prevents the other character from getting Lucy. They could say or imply that NaLu is only a thing because they're the hero and the heroine, and their relationship is lacking, unlike the other choices Lucy has
Those people ignore how the story crafts and highlights the solid chemistry and emotional attachment that makes the bond between Natsu and Lucy a potent relationship with the capability to grow into something stronger. Their best moments show they're each other's best choice.
