In February 1825 he married Julianne Thiemer, daughter of a property owner and well-established glove-maker in Seesen. Heinrich, a cabinet maker without property, a Beiwohner(boarder), was marrying up. Together, he and his wife raised ten children in Seesen, a small city of about three thousand people six miles down the mountain from Wolfshagen. (Steinway & Sons by Richard K. Lieberman)
How does marrying up work in this paragraph? Is there any difference if you use past tense here?