Nobody who saw the ending of the season's episode 4 (episode 28 total) should have genuinely anticipated that Issei was planning to be left dead. It was only a matter of what contrivance could be utilized to get him back from what were certainly fatal injuries. Loki's departing words indicate that some way of curse was placed as a takeaway on Issei, although its impact isn't clear from the conclusion of the episode.
Valkyrie and the demons had some help, yet. When she attempts to use Issei to forget (yes, for the reason that manner), some strange magic effect occurs which calls out her accurate memories of the time and helps her understand that she perhaps has not been completely honest about it all. Hence the episode finishes having a potential gesture of reconciliation; bento have frequently been utilized to symbolize one character's feelings towards another, but on this occasion it packs more significance, and therefore is more touching.