Lyric discussion by MedievalMadam 

Cover art for If You Could Only See lyrics by Tonic

I agree with Charisse.
Next best explanation is, a guy explaining to another girl why he can't leave his current girlfriend. He can't be with her because his current girl loves and trusts him, and he loves her. Going down that 'road less traveled' would definitely put a dent in his happiness, so he can't be with the other woman.