they were in love? Those words were never uttered in FC. No one can even say they would even be together by the time DOFP came to be a decade later, Your whole point is based on a bunch of maybes; maybes which maybe wouldnt have happened. IMO its a stretch to blame Magneto's problems in the 80s on something Xavier did in the 60s
It is not about them being in love and changing all the time line. Just staying in XMA:
The fact that Moira had repressed memory lead her to Apocalypse who is a nemesis of Charles. He represent the repressed memory. Everything he does in XMA Charles will end up doing, Charles will even repeat his world when freeing Jean. And he will get his own horsemen at the end:the X-Men.
Apocalypse first go to Ororo who is a thief, Charles will have to give back Moira memory, he was a thief too. Apocalypse got to free Psylocke of Caliban control, Charles will have to set Jean and Moira free. Apoczlyose gave Angel back his wing, Charles will allow Jean to fly by her own (the metaphor/link beetwen Angel and Jean was already in X3).
It is my interpretztion of it, my way of making sense of it. I look for clues, symbols ans similtude because it is what build emotions, the resonnance, that is what makes me all full of thrill when i'm watching the movies. Because the thing that are the most powerfull are those i do not see.
They clearly linked Jean's and Erik family, why would she have stab an arrow by the lake? That make the power of the scene where they are building the school together, the home, the family.