The first 4 dates on the page are: Dom. 3 p. Pascha = 3rd Sunday after Easter. (15 Apr 1731) Dom. 5 p. Pascha = 5th Sunday after Easter. (29 Apr 1731) Festo Ascension = Ascension Day. (03 May 1731) Dom. 6 p. Pascha = 6th Sunday after Easter. (06 May 1731)
Trolovelse is not a marriage, but an engagement (a marriage promise) that was made in the presence of a priest. Their engagement was on Ascension Day, ie May 3rd, 1731.
You're right. Their marriage date is "Dom. 7 p. Trinitatis", ie. the 7th Sunday after Trinitatis. Trinitatis was on May 20th in 1731, so they got married on Sunday July 8th.