Eka's Portal

I rarely see this in stories. So your pred has shrunken you, swallowed you, and you ended up being plopped on the floor ungracefully as part of a pile of her poop. How do things change in the future whenever you see her again?

Keep in mind youve seen the worst in her, you know what her insides are like probably better than she does herself, you've smelled all her internal smells plus her farts and scat as she was expelling you. You'll probably never be able to not cast a look her way when she casually mentions her stomach is feeling weird or crumbly or mentioned she has gas, because you've witnessed all that firsthand.

I think it might not be dissimilar to BDSM relationships. Pred's the dom, prey's sub, neither of you are being permanently harmed (hopefully).

With some extra jokes about "getting dumped".

Well, you've gone and set a lot of variables there. If it's "realistic" like that, but there was some existing relationship, I can only imagine it'd be soured except for masochists.

You say worst parts... I say best parts.
Im not really into unwilling or bdsm so I would see it based on either willing or unaware until release.The later would bring the biggest reaction as the pred would be extremelly embarassed and guilty whenever she saw the prey while the prey would feel awkward and weird around the pred.(but probably secretly have a desire to try again.)