While I get what you're saying, consider Arbert. While not in a relationship, he is a part of us. And Laimitt(Lamitt?) wanted that D so bad. Is that upsetting to you? Because it's literally the same logic. Our original self is not really us but something we once were with entirely different thoughts, appearance, memories, everything. The kid from the 14th is also a part of us. We, the WoL/D are not a child either nor did we share the same parents as said kid.
If Hades had a fling/thing/anything with who we used to be, it is not us personally. But as the player, you could accept or deny this as feelings carried over without diminishing that aspect.