Joseph Cannot Restrain Himself

Then Joseph was not able to restrain himself... (my translation)

The word here translated "to restrain" is a form (Hithpael Infinitive) of the Hebrew word אָפַֽק (˒ofāq). The idea of this sense of the word is "to control oneself"[1], but "restrain" is a helpful translation in view of how the word is used in Scripture. It is used when a person feels a powerful or overwhelming emotion or longing, but restrains himself from acting on it, for a time at least.

Earlier, in Genesis 43.31, Joseph feels the some powerful longing to reveal himself to his brothers, but at that time he is successful in restraining himself.
In Esther 5.10, a more negative example is provided, where the wicked Haman is filled with violent wrath towards Mordecai, but chooses not to act immediatedly against Mordecai.
In the book of Isaiah, God himself is shown to have deep feelings of compassion towards his people, yet for some mysterious reason does not yet act to end the suffering of his people (Isaiah 63.15). See also Isaiah 42.14 and 64.11 for interesting uses of this word.

See that Joseph, presented throughout his story as an ideal godly character, is not a dispassionate, emotionless individual. Rather, he is full of a warm and tender affection toward his long-lost brothers. This is all the more remarkable, as we would expect instead bitterness and anger, in view of what they had done to him.

Likewise, our Creator God is not a dispassionate being, or simply some cold, cosmic supercomputer. Rather, the depth and power of his emotions, of his feelings and longings toward us, are overwhelmingly beyond our comprehension.

Emotions are not all that we are or all that are important. We must sometimes restrain or control how we act on our emotions. But as we are transformed into the image of the Christ, we are able to feel and to express the depth of our emotions as God meant for them to be.

[1] see HALOT