Lois is what Superman loves about humanity. She’s who he tries to be, and reflect back to him the hopes he has for what we can become. She has no amazing powers but that never stops and, if anything, pushes her further. Lois Lane is the single most important character in the Superman sphere, outside of Superman himself.
Without that reflection/desire Superman, and Clark, becomes shallow. He wants the world to be this big hope inspired thing but that’s just words at some level. With Lois in the mix suddenly he has a concrete example. He can point to her and go “This, this is what you could be,” and so of course he loves her.
She’s his idol, in so many ways.