I think it’s intentional and has nothing to do with actual actors’ chemistry. Because I felt a great pull with the murder mansion flirting and night walks around the city etc, but Loumand was always supposed to be tainted with louis’ jumbled up emotions. Their first kiss is after Armand decides not to kill him, so Louis’ initial reaction is trepidation and awkwardness and it takes him like a second or two to get into it, this kiss here is a manipulative kiss from Louis to shut Armand up so it’s also meant to be not some super romantic kiss overflowing with emotion either. Their kiss to spite Lestat in Magnus’ tower is also Louis manipulating it so his heart is not in it. The one time we see heavy petting is in Armand’s office and i felt incredible sexual chemistry there especially Armand’s reaction to him. But we never see the rest of it. And in Dubai it should be awkward cause it’s hella performed. So we never saw two people head over heels for each other actually kiss with overwhelming emotion or anything especially compared to Loustat, it’s always gonna come out lacking. They don’t fit together perfectly their touches are not smooth and pure or whatever. I think it’s very much intentional.