It's a combination of: this is a super
"off-duty" picture; they are exceptionally lovely and happy and sweet together here... and Astrid, who seems about to laugh her head off.
(Small side inquiry of 'Leo did you do
that to her dress, or are you trying to make it better'? ...Or both.
I wouldn't be surprised if they were on honeymoon (they both look so young), but I wouldn't be surprised if it were some other time.