I can't lie; I understand how Caleb's movie inspiration comes off as disappointing. Don't get me wrong - Up is a wonderful movie. It's incredibly moving, deep, and beautifully animated.
Up is not a ROMANCE movie. What we are seeing in this movie is the aftermath of the relationship. The romance itself is already finished, replaced with an allegory of living life past your grief. And this can apply to any kind of loss, not just romantic loss.
Also, and this is very important, the relationship that develops in Up and makes up the very core of the story is the familial relationship between Carl and Russell. It is Russell's presence that inspires Carl to move on from his grief and let go of his past.
Yes, Up is a movie that fits CalebMC very well. But when placed next to the other LI romantic cards whose source of inspiration come from actual romance stories, I can see why a lot of Caleb mains feel left out.