So that demon's GF gave him a call to break up with him, because she was unhappy in their relationship, but AFTER she found someone new. Mangaka, you can draw her and that new BF as nice and sympathetic as you like, but she is a cheating bitch.
Just swap the genders for fun a bit: "Hey, Charlotte! It's me, Chad. Your boyfriend, who is keeping our interaction as low as possible lately. I
called you to break up with you, because it's less messy for me this way and because I wanted to tell you I found a new girl. It has been fu...nice being with you, but she is more wife-material, then you have been. For example, she has a save steady income on her own and you don't. Also, your
"whatever Charlotte takes pride in" sucks. Actually those
"prided things" and you are kinda creeping me out, so you shouldn't have gifted them to me in first place. I never appreciated them anyway. Ciao." *hangs up*
Now tell me, that guy (Chad) isn't a unredeemable bastard.
Too bad demon lost his time on that harlot. And as far as revenge on that other guy goes, (if he ever knew they still have been an item), he won her! That's punishment enough. But to make sure, he should totally bring her stuff over to him. XD
"Hey there. This is my short time-Ex's stuff."
...
"Huh? Short time-Ex, because she just broke up with recently (via phone) and meet with me until then." (not really lying)
...
"Oh, wow. (If there has been a mandatory meeting day
Well we have always been meeting on >mandatory day< But sure, you can call me a liar, if you want. I don't wanna get involved in your relationship, as she is now all yours."
...
"Well, FU2."
Just go with the truth. Truth is always best!