Spottedleaf and Firestar. If Spottedleaf wasn't killed and she and Firestar fell in love. Spottedleaf was younger and she was a trained warrior.
Leafpool and Crowfeather ran off together and Leafpool did return to Thunderclan to help heal, but she left Thunderclan after to be with Crowfeather in Windclan. In Windclan, her kits were still born, but the prophecy of the cats with the power of the stars was still fulfilled in Windclan.
When Jayfeather dies,he is reunited with Half Moon in the ancient tribe. Together they remained in Starclan.