Lyric discussion by smigler 

Cover art for Relief lyrics by Chris Garneau

My take on those two tricky lines is:

"...a sweeter sin, a sweeter sin in red." possibly referring to the "good ol friend" as the "sweeter sin" wearing something red.

or

"...as sweet as sin, as sweet as sin in red." referring to your "words" as sweet as sin.

As for the eyes on the clouds...I don't hear it that way. To me he is clearly saying, ..."nose to nose, eyes all closed" Listen to the background singer.

He is talking about a deep passionate kiss, nose to nose, with eyes closed. This is where he gets the forgiveness he is seeking in the form of a kiss. After the kiss, he quietly apologizes again.

My Interpretation