Has τέλος meaning "end" and τέλεια meaning "perfect" some sort of correlation? By perfect meaning that perficio from Latin means "finish, complete"? When one is perfect then one is complete? Love languages...
Once a teacher of mine said that when you consider someone to be perfect, you wouldn't change them at all, so they are, in a sense, complete. It's interesting that the same happens in Greek, isn't it?
It is explained in the possessives' tips and notes, under the Double accent rule.
Perhaps not in the app, but you may be able to access them by visiting https://www.duolingo.com/ from the browser on your mobile device.
It may be necessary to "request Desktop site" and/or try various browser (I've heard the Puffin browser may be helpful, but haven't tried this myself).
When "σύζυγός" means both, "wife" and "husband", then shouldn't "my husband is perfect" also count as right? (Or is there a hidden gender hint I did not notice?)
I did the same thing, then checked the comments to find out why I was wrong. Did I ever feel silly when the obvious was pointed out, LOL!