Soubhagya, I think the easiest way to explain how Clark looks at Krypton is like this;
When someone dies, some people have a mournful, sad funeral where everyone cries and laments the death.
Other people have a party and celebrate the life.
That's how Superman looks at Krypton. He celebrates what it was, he doesn't wallow in it not being around anymore.
I do think it carries a certain burden on him, but its not a "sad" kind of burden. And keep in mind, the loss of an entire species is a completely different thing than what any of us can really comprehend. Saying that he wouldn't think of it as anything more than a "curious memento" rings false to me; Clark has too deep a sense of responsibility to just wave off being the last of his kind and not invest emotionally and intellectually in it. He'd want to preserve that culture as much as he could. But that doesnt mean he has to be super sad about it all the time, or that he doesnt appreciate and love his adopted world and the family he's made here.
He can do both things; love earth and the Kents and have a happy, full life, while also embracing his culture and keeping the memory of Krypton alive.