Lady Mary Crawley and Matthew Crawley
After a two-year estrangement, the back and forth between distant cousins Matthew (Dan Stevens) and Lady Mary (Michelle Dockery) continued in the second season as they were both engaged to other people. A war injury left Matthew paralyzed (and impotent), so he broke off his engagement to Lavinia Swire (Zoe Boyle). Mary's steadfast care for wheelchair-bound Matthew upsets her newspaper publisher fiancé Sir Richard Carlisle (Iain Glen), who kept her at bay with damning information about her affair with a Turkish diplomat. Sir Richard brought Lavinia back to Downton where, after a miraculous recovery, Matthew renewed their engagement. But Matthew's abiding feelings for Mary and Lavinia's contraction of the Spanish Flu set back the nuptials. Lavinia, seeing Matthew's love for Mary, told him on her deathbed to be happy, but Matthew still blamed himself and Mary for his fiancée's death. Despite Sir Richard's threats, Mary eventually called off her engagement and revealed her dark secret to Matthew. Though the news was hard to take, Matthew promised he could never hate Mary and finally dropped to one knee and proposed for the third time. Mary tearfully accepted. Let's hope it sticks this time.