Flaure and Inferno's friendship in particular, which technically started the RP. No matter how much time has passed, or how their goals in life have changed, they are still best friends. To quote Flaure,
"Forget about helping me fight. I dont care that you changed. Ill protect you this time, I promise. Youve been so good to me, despite my disregard, and Im going to fix this as much as I can."
From what we get to see (before things go to hell) Inferno and Vincent's marriage. They're supportive of each other, love one another, and even resolve fights quickly enough. Just a happy young couple that want a family.
Iouri's very obvious care for Flaure on more than just a 'partner' level. His utter destructive panic when she nearly dies, and all interactions since are examples of Aww, Look! They Really Do Love Each Other