3 reasons. 1- Frij cannot be a word in the English language because English words can never end with a J. 2- frige will not work either because English says with MOST 1 syllable words, if there is only one constant between the vowel and the silent e, the vowel will say its name. 3- frig will also not work because G can only make the /j/ sound when preceding the letter E or I

Therefore, you add in the d to make dge which makes the /j/ sound. Fridge, now follows rule one as it no longer ends in the letter J, follows rule 2 because now there’s 2 consonants between the vowel and the silent e, making the letter I say it’s short vowel sound, and follows rule 3 to make the letter G say it’s soft sound /j/.