To fit or go well together; used when people or things match comfortably or when an idea/solution feels right. Almost the same as しっくりくる.
新しいチームメンバーとは意外とすぐにしっくり行った。
I unexpectedly got along well with the new team member right away.
この色は部屋の雰囲気にしっくり行かない気がする。
I feel this color doesn't really fit the room's atmosphere.
いろいろ試したが、このやり方が一番しっくり行く。
I tried many methods, but this one fits best.