I told him it's time to part ways when I was working with the Grey Beards but now I went to re recruit him and I cannot find him. I'm nervous that he died on his way home - can that happen or do I just need to wait a while? He has all my good loot that I didn't want to carry, so I really need to find him.
Where Do I Find Him?
Faendal lives at the town of Riverwood, so try going to Riverwood. Normally he's seen carrying wood back and fourth near the lumber mill, or even at his house (near the back of the town, near Ralof's friend's house).
If you can't find him, wait for a few hours/days and he might appear.
Did He Die On The Way Home?
The fact that he died on his way home is false, due to game chunks (the only exception is if you were at the location where Faendal is getting killed, but you said you looked in Riverwood and you were at High Hrothgar.
I would follow this page: https://gamefaqs.gamespot.com/pc/615805-the-elder-scrolls-v-skyrim/answers/300694-what-is-the-console-command-for-moving-an-npc-to-you-or-you-to-it and this page to find his code: http://elderscrolls.wikia.com/wiki/Faendal
then press the key to the left of the 1 (`) to open the in-game console.
Press the (`) key, then type prid 0001348c (then the ENTER key) resurrect (then the ENTER key) (which should now give you some letters and numbers) then type player.moveto 0001348c (then the ENTER key). to bring him to you. If he's dead, you may have to enter "resurrect 0001348C".