Love of her life? Iida in the original doujin version of Karami Zakari only loves sex, her relation to Kousei is completely parasitic in it, Iida only got raped once in the doujin version during the spring festival, she becomes such a nymphomanic that every other following event where a slimy fuck try to take advantage of her Iida welcomes it with open arms, any opportunity to have sex is good a time for her by then.
Iida had become so sex crazed that she just stops hanging around her friends and Kousei all the way to graduation, even a lesser nympho like Miiyama felt she was getting left behind and slighted by Iida, no wonder she managed to score a happy ending for herself by realizing marrying your childhood friend is better than ending up as a forever loose slut.
Although I shouldn't rip on Iida too much since Kousei is equally crazy, the guy is a total enabler in the doujin version, a utter loon of a cuckold that never confessed to Iida in a conventional manner either, he would rather ask Iida to continue living for sex encounters to fulfill his cuckold fantasies.
The fact a surprise new development just happened 6 years since the original ending had Kousei move on and marry someone else is ironic in a way, in the end it was Kousei that used Iida and left her as a aimless girl that can only find meaning in having sex for the sake of thrills, Iida did form a connection with Kousei as she hopelessly sends him an orgy live feed the day of his ceremony, but Iida is so gone by then that she can't process real love anymore, just a bizarre wish to feel Kousei still needed her to fulfill his fantasies.
In the end, Iida only loves Kousei in an conventional manner in the Manga remake version where her feelings for him are actually real and she isn't such an insane nympho like her original doujin self.