to become soggy or swollen from soaking; to soften and go mushy after absorbing liquid
濡れたパンが皿の上でふやけてしまった。
The wet bread went soggy on the plate.
長くお風呂に入っていると指先がふやける。
If you stay in the bath for a long time, your fingertips get pruny.
ページが濡れて本がふやけてしまった。
The pages got wet and the book went soggy.
to become lazy or slack (mentally); to lose motivation or become indulgently laid-back
夏休みが長すぎると、仕事への意欲がふやけてしまうことがある。
If summer vacation is too long, sometimes one's motivation for work weakens.
最近、運動をさぼってばかりで意志がふやけてきた。
Lately I've been skipping exercise and my willpower has been getting weak.