There is a character, an older male, in this manga that I'm reading who uses this phrase twice
しないとな and the two lines are like this:
- お礼をしないとな
- お別れをしないとな
The first line, he is referring to himself (I should show my gratitude)-->I understood it more like "It wouldn't do if I don't show my gratitude" "I have/must...(among these ideas). It was more clear when the character said his 2nd line which I interpreted as: Say your goodbyes/Say farewell (note, he was directing this to another character that was with him).
I hope I made sense...What exactly is the usage of と here? What does it express? And does the 1st line sound okay with the interpretations I gave?
Thank you!