The devas wanted Paarvati who grew up as the daughter of Himavan and Siva Who was performing yoaga to unite and perform their five-fold functions. They believed that without this union the birth of a son who would kill Sooran will not be possible. Not waiting patiently for Siva to complete His meditation they send Kaaman, the god of love, to disturb the penance and to make Siva fall in love with Paarvati. Kaaman was burnt by Siva’s third eye. When He completed His tapas in due course, Siva, out of compassion for the souls decided to perform His functions together with His Shakthi. Their holy marriage, according to the KanthapuraaNam was held on the auspicious day when the Uttharam asterism conjoins with the full moon. This happens in the month of Pangkuni. This day, suitable for worshipping Siva as ThirukkalyaNa Sunthararm, is also the day that gave the devas and others the hope that Kumara will be born. Hence it is also celebrated in the temples of Murukan.
From the book titled, The Worship of Murukan by Dr. (Mrs.) Devapoopathy Nadarajah