Genesis 38:12

‘And in process of time Shua's daughter, the wife Judah, died, and Judah was comforted and went up to his sheep shearers to Timnah, he and his friend Hirah the Adullamite.'

In the meanwhile Judah's wife also dies. This is what makes what follows possible. Had she still been alive Tamar might not have done what she did. But once she learns of the death of her mother-in-law her mind turns in that direction.

“Judah was comforted.” The period of mourning comes to an end and Judah begins to live life again. It may be or not be that Judah genuinely grieved for her loss, either way the mourning ritual must be carried through. Until that had happened he could not join the sheep shearers in their celebrations at the time of sheep shearing which was a time of feasting (see 1 Samuel 25:11; 2 Samuel 13:23 on).

“Went up to his sheep shearers.” He takes with him his old friend Hirah, who has possibly helped him through his difficult time, and joins his sheep shearers to watch over the work and join in the celebrations.