Matching And Sorting Non-Identical Row Pairs

I have a database with 6 columns in play (there are actually other columns but they are not relevant). I'll call the columns A through F. I would like to be able to match certain counterpart rows together, do a sort placing the counterpart rows adjacent to one another, and then count how many pairs I have. (Some rows will have no counterparts.)

Here is a micro-illustration of the database:

______A______B______C______D________E_____F
R1___01-03___54____959____nsneakr___24____yes
R2___01-04___67____454____adidaht____53____yes
R3___01-10___42____344____calb3wd___11____no
R4___01-19___67____454____adidaht____53____no
R5___01-25___54____959____nsneakr___24____yes
R6___02-02___54____959____nsneakr___24____no
R7___02-14___54____959____nsneakr___24____no

I basically need to devise a formula or script that pairs together two rows that fit the following criteria:

1) The rows are identical in Columns B, C, D, and E.
2) The rows are not identical in Column F (i.e., one half of the pair should have "yes" and the other half should have "no")
3) The rows are as close together as possible according to the date sequence in Column A. For example, Row 1 should pair with Row 6, and Row 5 should pair with Row 7. Row 1 should not pair with Row 7, and Row 5 should not pair with Row 6. **This criterion seems tricky because R5 and R6 would technically fit the requirement for pairing, were it not for the fact that R1 comes earlier in the sequence.**