C. F. Keil and Franz Delitzsch on Ecclesiastes 3:8

Ecc 3:8 “To love has its time, and to hate has its time; war has its time, and peace has its time.” In the two pairs of contrasts here, the contents of the first are, not exclusively indeed (Psa 120:7), but yet chiefly referred to the mutual relations of peoples. It is the result of thoughtful intention that the quodlibet of 2 x 7 pairs terminates this for and against in “peace;” and, besides, the author has made the termination emphatic by this, that here “instead of infinitives, he introduces proper nouns” (Hitz.).