It's just that based on what Kaveh's gone through, he isnt ready to face his emotions yet. He still thinks of them as former friends and wanted to have a chance to rebuilt it. On the other hand, there's Alhaitham who offered his home and shared the comfort of his place for the other. He'd pay for the other's tab and pick him up from lambad's.

It's just that they care for each other but have different ways of showing it. Also, Alhaitham is an unreliable narrator so you need to carefully check their scenes together and analyze it based on their respective voicelines.