Structurally a four-character set phrase:
悲 ('sad') +
喜 ('happy') +
交加 ('coming together'). Same pattern as
风雨交加 ('wind and rain together' = stormy) and
饥寒交加 ('hunger and cold together' = destitute). Reserve for emotionally intense moments - reunions, graduations, partings - not for everyday mood mixing.
