Rachel was the true zeevug (soulmate) of Yaakov. You having a child with her was his most prized possession.. and it tells you what Yosef's meant to him.

The Torah tells us that when Yosef's first son was born, “Yosef called the name of the firstborn Manasheh for ‘Yahhas made me forget all my hardship and all my father's household'”, Yosef wished to express his thanks and praise to Yahuah for causing him to forget his hardship so he named his firstborn Manasheh (In Hebrew `Nashani' means “caused me to forget”). In the pasuk his “father's household” refers to Yosef's brothers. Why did Yosef feel so fortunate that Yahuah caused him to forget his hardship and what his brothers had done to him? One may think that it may be important to remember suffering in order to be reminded of one's fallibility and keep one humble. Yosef did not say that his suffering had ended; he merely wanted to give thanks and praise to Yahuah.