This might be hard for me to put into words, but... I don't think Kizuna and 02TB have a character villain. At least, they're not pure evil like people want them to be...?
It's easy to watch these movies and then come to the conclusion that both Menoa and Ukkomon are the villains of them because of their actions and wrong choices, but the real thing is neither of them had malicious intentions and they only wanted to help people or their own partners..
They were good people who did bad things. I'm not saying they didn't do anything wrong -- because they did, and none of the movies sugarcoated their actions and justified them -- and yes, that they were characters with noble and good intentions who ended up screwing things up really badly because of something related to the plot and themes of the movies.
What I'm trying to say is that the real evil villains are not the characters and yes, something "abstract" -- something I also see in the 02 TV series and Hurricane Touchdown movie.
Kizuna's villain is the pressure young people feel to grow up, which makes them clueless about what it means to be an "adult", and thus they reject their beloved childhood memories and hobbies in order to become mature and older.
This theme is depicted not only in the Partnership Dissolution's dilemma, but also in how Taichi, Yamato, and Menoa (and to some extent Sora in the short "To Sora") reject their Digimon partners in order to become "real adults".
Menoa's entire mental health is shattered to the point that when she loses Morphomon, she assumes that becoming an adult is a bad thing, so everyone should stay a child to prevent more people from suffering the same pain. But does that make Menoa a bad person? No, because she wanted to help people and prevent others from having the same "fate". Her actions were bad, but not herself or her intentions.
Meanwhile, 02TB's villain(s) are the miscommunication between you and the people around you, and the cycle of family/domestic abuse.
The theme is pretty much represented in the Ohwada family, Ukkomon and their actions. Rui was a victim of family abuse and I guess he never had a chance to make his own choices or express his own thoughts and needs, so Ukkomon comes in and just saves him from that miserable life by doing wrong things. But since Rui never had a really good example of how to communicate and deal with people in general, he messes that up as well by passing on the same abuse he suffered to Ukkomon -- which is shown in the scene where everything in Rui's life goes south.
Does this mean that Ukkomon and Rui are bad people? No, they're pretty good people with good intentions, but they make bad decisions and do wrong things in the end. Both Rui and Ukkomon claim to have done bad things, so I'm not blaming the victim here.
As I said, this narrative with an "abstract" villain is also present in 02 and Hurricane Touchdown, unlike the more traditional and usual cartoonish villains in Adv'99 (or in the Adv reboot/2020 anime), OWG (+ DSB), and in Tri as well -- Because Ken, Oikawa, and Chocomon were NOT bad people either, just good people doing bad things and making wrong choices..