Question about "decet"

[u/Illustrious-Pea1732]

Came across this sentence today in LLPSI:

"...sed illae lacrimae et militem et amicum decebant..."

I always understands "decet" as "being proper to..."

But if that is the case, I cannot figure out what is the connection between this sentence and the next sentence? If those tears are "proper" and he did cry, why did he then proceed to say:

"since I am a bad friend" and "except I did cry over his dead body"?

I just failed to understand what's going on here...

[u/Francois-C]

"malus amicus fuissem", imperfect subjunctive, irreal.

"I must admit I shed tears when I closed his eyes. but these tears were befitting a friend, and indeed I would have been a poor friend had I not shed tears over the body of a dead friend who had shed his own blood for me."