I'm starting a band (currently 2 piece acoustic versions of heavier songs which will be played in a full band once we get going). I've taken the driving force role, as I have much more experience with music and songwriting/study it at college. The singer, who is a good mate of mine has a sweet voice so I'm getting him to sing while I play guitar and do backing vocals. The difficulty arises in the fact that I write all the music and lyrics (he's not very musical). I write songs about issues and events which matter to my life, however it's obvious that he may or may not feel as strongly, if at all about the topics. I try to write in a somewhat ambiguous manner so that anyone, not just him, can relate to them. Any advice for someone in this situation? Anyone been there before? I want to be able to write about things that matters to me, but don't want to expect him to compromise how he feels. Man this has become a long post. Looks like I'll need a...

TL;DR: Singer doesn't write the lyrics, guitarist does. Anyone else had problems with sentiment or subject and how the singer might relate?
As a singer it's his job to sing the lyrics convincingly, loads of bands have songs written by other members.

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Give him the lyrics and play the music, let him work out a vocal line and see what happens. Sometimes the way it's sung means more than what's said.
You should speak to the singer about it. He might not have a problem with it. Singers in cover bands sing all sorts of songs that don't necessarily reflect their feelings.