a dagger, a dagger, please fetch me a dagger

In the case of Kaveh and Alhaitham, this is pretty straightforward. I LOVE Kaveh, but this guy can canonically not stop ranting about Alhaitham. Other characters have commented on it, how Kaveh brings Alhaitham up in every other conversation... Kaveh drinks heavily too, makes bad financial calls and most crucially, feels like nobody in the entire world truly understands him. He has this tortured artistic soul thing going for him, and struggles to find anybody who he feels simply 'gets it'.

If Kaveh went on a date, how long would it take for him to bring up Alhaitham? And if he didn't and if it worked out, would he really be able to find another human being who's as patient with him? As willing to provide and carry him home from the tavern, someone who can and is willing to put in copious effort to overthrow Alhaitham for thr title of "knows Kaveh best?"

Not really.

On Alhaitham's end it's even more obvious, the suggestion he might open up to allow literally anyone else into his space is borderline ridiculous. Alhaitham tolerates most people, the fact he invited Kaveh to live with him and is spending all this mental and physical energy on them is telling enough. Do you imagine Alhaitham ever caring for someone more than he does for Kaveh? No. Absolutely not.

That's not even going into how other people genuinely don't understand him (and not just in romance either). I feel like a romantic relationship with someone other than Alhaitham could be fulfilling in some aspects- but ultimately come up short. It would only be a fraction of what he wanted from a relationship.

Though, it is interesting how he equates mortality to powerlessness. Plenty of people in teyvat are mortal yet possess great strength. Is it the idea that old age will claim his bones some day like it did with Adorno? (and Varka, to some extent)

Selections from the book, Noise 3, by legendary design firm, The Attik (book published 1997, selections are from the early-mid 1990s)