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to melt into; to dissolve into; to merge into
to blend into (surroundings); to fit in; to adapt to; to integrate
塩が水に解け込むまでよくかき混ぜる。
Stir well until the salt dissolves into the water.
留学先の文化に徐々に解け込むことができた。
I was gradually able to blend into the culture of the country I studied in.
彼女はなかなか集団に解け込むことができなかった。
She had a hard time fitting into the group.