Look at the shoulder level on that photo.
There are no nice ways to say it, so I'll just say it like it is: Ana's head is bigger than Adam's.
Women are notoriously bad judges of height, and they all think they are taller than they are.
Seriously, it's not that her judgement about her height really matters. The height is measurable. Her impression is irrelevant.
It's strange, but girls like being tall. Ana once said she would have liked being even taller than she is now. And then there is WTA marketing of beautiful Amazons playing tennis.
Have you seen her in nature? She's huge, it's not marketing.
Fernando Verdasco, 1.88 m
Novak Djokovic, 1.88m
They both are taller than her, but it might be 2 or 3 cm.
There is no explanation for that photo where Ana is wearing high heels and they are the same height. Only if Adam is insecure and wearing elevator shoes.
Ana looks kinda stooped at most of those pics. But she still looks taller. And I don't think those hills are too high, it would be inappropriate, since he's not very tall.