both of your choices are correct in respect to the double couple part...but how i would justify is by comparing the two guys and the two girl to see if they are on even grounds.
therefore i won't include the following:
better halves..if moses and joyce are main then the 3rd couple should be included too
detective investigation files 3..the two guys and two girls are not of equal importance
the last breakthrough..nick and raymond may be close to equal but sonjia > leila