4862. 'For she saw that Shelah had grown up, and she had not been given to him as a wife' means the insight that it could not otherwise be joined to the semblance of religion existing among those descended from Jacob, specifically those descended through Judah. This is clear from the meaning of 'seeing' as an insight, dealt with in 2150, 2325, 3764, 3863, 4403-4421. The reason this was the insight - that it could not otherwise be joined to the semblance of religion existing among the descendants of Jacob, specifically among those descended through Judah - is that 'Judah' means those descendants, 4815, 4842, 4852, and therefore the semblance of religion existing among them, to which it was joined because it could not be joined to Shelah. Also, 'Shelah' represents idolatry, 4825, 4826, 4845, to which the truth of the representative Church meant by 'Tamar' could not be joined.
Arcana Coelestia # 2150
2150. 'And he saw' means when He recognized this. This is clear from the meaning in the internal sense of 'seeing' as understanding and recognizing, and also of becoming enlightened, dealt with in 1584. Nothing is more common in the Word than for 'seeing' to have such meanings Here the meaning is that He recognized the presence of perception from the Divine, as just stated.