No you're on the right track. I like Sakura and it would be hard for me to say this, but she would have to essentially become near nympho levels of "fallen" in order for it to be karma, and at that point you'd almost have to feel bad for fuckboi in a way because it means that he does "love" her to that extent, but I won't be sympathizing one bit because of what the two of them did to Shinobu. Doesn't matter how genuine fucboi's love for Sakura is, Shinobu was the the one there for her first and did way more than finding a necklace and praying at some love shrine could ever equate.