what is the poetic device used in the line 'both wry with the laboured ease of loss'?

The poetic device used in the line "Both wry with the laboured ease" in the poem 'A Photograph' is an oxymoron. In this line the poetess is talking about her mother's past as well as her own past. The holiday at the beach is the mother's past while the poet's past is remembering her mother's laughter when she looks at the photograph. In this line it has been expressed by the poetess that both these events are filled with delightful memories which give them a gloomy or dry pleasure when they remember of it. The poetic device oxymoron is used in the contradictory words "laboured ease". These contradictory words have been used to describe the sad feeling of loss which comes by thinking of the past which was beautiful and happy for both the poetess and her mother.