A solution where all pairs of guys and gals play with and against each other at least once is possible. It would also be nice to distribute the byes so that no player has two byes in a row, and furthermore that each player has, two games in rounds 1-3, two games in rounds 4-6 and their last two games in rounds 7-9. It is possible, but it seems the only way of doing this, is to keep the players in the same groups of 4 when it comes to the byes. I hope the schedule below is useful.
Net 1 Net 2 Byes
[(M5 F5):(M3 F4)] [(M4 F3):(M6 F6)] [M1 M2 F1 F2]
[(M6 F5):(M2 F2)] [(M5 F6):(M1 F1)] [M3 M4 F3 F4]
[(M1 F3):(M3 F2)] [(M4 F1):(M2 F4)] [M5 M6 F5 F6]
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[(M1 F6):(M2 F5)] [(M5 F1):(M6 F2)] [M3 M4 F3 F4]
[(M4 F4):(M1 F2)] [(M2 F1):(M3 F3)] [M5 M6 F5 F6]
[(M5 F3):(M4 F5)] [(M6 F4):(M3 F6)] [M1 M2 F1 F2]
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[(M2 F6):(M5 F2)] [(M6 F1):(M1 F5)] [M3 M4 F3 F4]
[(M5 F4):(M6 F3)] [(M4 F2):(M3 F1)] [M1 M2 F5 F6]
[(M3 F5):(M4 F6)] [(M1 F4):(M2 F3)] [M5 M6 F1 F2]
Note added later: I have corrected the female byes in the last two rounds above, in the initial version these byes were given the wrong way around.