To begin, Andrew Marvell lived and wrote in the 17th century, and his political views shifted throughout his life and career. Particularly in his later works, Marvell was somewhat critical of the rigidity of the established church and royal court of England.
"The Mower's Song" is a poem about unrequited love, but it is not only a poem about a broken heart. The mower is at odds with the classic English meadows; he suddenly resents them and the brutal manicuring he does to them as the mower. This correlates to Marvell's resentment of the self-indulgent, formal, and materialistic nature of institutions. Just as the growth of the meadow is impeded by the destructive mower, so too is progress impeded by the stodgy values of church and royalty.
Consider the following lines from the poem:
Unthankful meadows, could you soA fellowship so true forgo?And in your gaudy May-games meetWhile I lay trodden under feet?