The poem is built on a simple, repeating pattern: she does something, and he grins. She rolls her eyes, smiles, ruffles her hair, laughs, and each time his reaction stays exactly the same. That sameness makes him seem completely taken with her, as if nothing she does could make him feel anything else. The repetition also works like a slideshow, with each line a different picture flicking past.
The last line shifts things. "Lately his mind was streaming through her snaps" suggests that the scenes above are not happening in front of him now but are being replayed in his head, or through photos of her. The word "lately" hints that this has become a habit, and that she may no longer be there in person. The poem never says why, so that gap is left for the reader to fill.
The mood is warm and affectionate, but with a quiet ache underneath. The cheerful grinning contrasts with the stillness of looking back, and the closing sign-off, "Warm wishes and Regards," adds an oddly formal, distant note.