Perhaps it's their personalities. If Ryu is very artistic and Abel is more of a science - minded person, their different perspectives might make their love story unique.
I'm not sure who Ryu and Abel are in this context. But generally, a love story might involve how they met, the first impression they had on each other, and the moments that made their relationship special.
Well, the Bella and Abel love story could be one of great passion. Maybe they met by chance, like at a local fair. Abel might have been drawn to Bella's kind eyes first. They started talking and found they had so many things in common, such as their love for reading and long walks in the park. As time passed, their friendship grew into love.
The story of Abel and Cain was a story in the Bible, recorded in Genesis. Abel was a shepherd, Cain was a farmer. They worshiped God together and each offered sacrifices to God. However, God only accepted Abel's sacrifice, not Cain's. Cain was so angry and jealous that he killed Abel. God rebuked Cain and announced his punishment, making him a fugitive. Cain thought that the punishment was too heavy and was worried that someone would come to avenge Abel. God gave Cain a mark as a warning to stop people from hurting him. This story revealed the sins of mankind and God's judgment, as well as the injustice of Abel and the consequences of Cain.
There isn't an official canonical love story between Ryu and Chun - Li in the mainline Street Fighter lore. They are more like comrades who share a common goal of fighting in the world of martial arts tournaments. Ryu is mainly focused on his self - improvement in martial arts and his inner struggle with the Satsui no Hado, while Chun - Li is dedicated to avenging her father and fighting for justice.
The story of Cain and Abel is from the Bible. Cain and Abel were brothers. Cain became jealous of Abel because God favored Abel's offering, and Cain ended up killing Abel.