When llamas "love" you, it doesn't show hearts and you can't control them, but you can open their inventory and put in a carpet.
Linked issues
Comments 3
Baby llamas also don't show green particles when being fed wheat or hay to grow them (unlike other animals). Should I open a different report, or will this be covered?
The fact that you can't control them is intentional. The heart bug is most likely an issue.