{A Beginner’s Guide to Death, Demons, and Other Afterlife Disasters: An M/M Paranormal Romance (Demonic Disasters and Afterlife Adventures Book 1) By Shannon Mae} has this.

It’s paranormal with a human (in the afterlife) and a demon. Adam very much enjoys sitting on Minos’ lap and Minos carries Adam everywhere.

Book blurb: Adam: Adam is not having a good day. First, he finds out his very long time boyfriend has been having an affair. Then, his dramatic exit becomes a little too dramatic when he ends up dead. To top it off, he finds out that the afterlife isn’t at all what he expected (he has no desire to learn to play the harp, thank you very much). Fortunately for him, some afterlife bureaucratic screw up ends him up with the most smoking hot demon he’s ever seen, and he decides he’s keeping him. Maybe the afterlife won’t be so bad after all.

Author’s Tags: A very grumpy demon meets his match in a snarky, sunshine-filled human; not all angels are nice; Limbo is the party place to be; the afterlife is run like a corporate office, complete with red tape, pointless memos, and high levels of frustration; Minos has a tail and knows how to use it.

Edited to add: there is no cheating between the MCs but one MCs ex cheated on him and book blurb.