We don’t talk about the reason Zoro was so close to dying during thriller bark.
Like yes, it was for Luffy, he took his place with ease, not even thinking about it because it was luffy. He offered his life differently than Sanji did. Sanji saw Zoro sacrificing himself and Sanji couldn’t allow that because in that moment we saw that in Sanjis mind, he thought replaceable to the crew. (Which obv. Isn’t true).
But Zoro didn’t do it out of a lack of self worth, he saw luffy and couldn’t bear the sight of him gone. Zoro, whether he admits it or not, sees Luffy as something to behold, something that lives above others and shines a light that must be seen by all eyes.
On top of all that, he took all of Luffys pain. Not only did he take it all, he jumped head first into it, despite knowing how it would most likely be the end of him. He quite literally lept into all the pain and suffering Luffy had received without a second thought.
And on top of THAT… Zoro said it was “nothing at all”, not only because to him, it was nothing, what he did in his mind wasn’t something worth mulling over— sacrificing himself for Luffy is “nothing at all”. Also, Zoro knew that if Luffy knew the truth behind his pain, he would never forgive himself for being the reason behind his first mates suffering.
Whether you ship Zoro and Luffy or not, you cannot deny the love, adoration and pure devotion Zoro holds for Luffy.