Maybe that's why Spawn Astarion wasn't added kissing in the epilogue? I have various headcanons on this topic. He doesn't like touching in public...
Seems there's some banter contradicting this? Description for this banter is "Astarion Vampire Spawn" and the title specifies it's for act 3, so I'm assuming it's exclusively for Post-ritual Spawn Astarion:
Quote
Lae'zel: Astarion, I note you and your lover struggle to keep your hands off one another. Lae'zel: It makes you less watchful. We're panting after battle, and already your maws are glued. Astarion: We're having fun. I would say 'try it, it won't kill you', but in your case I'm not sure.
The language here is indeed colorful to say the least but it sounds like he's that kind of person that is annoyingly gratuitous about PDA.