What contributes to Marion's personality and desires as they seem to conflict with George's?
Differing perceptions of reality are what contribute to Marion's personality and its inevitable conflict with George. George pursues Marion, but fails to heed warnings that there might be a difference in paradigm when she says she will refuse his proposals unless she is confident that George can provide a comfortable life for her. Marion has no desire to examine the decaying condition of commercial enterprise and economic growth. Her only fear is that she won't be able to be a part of it. She actively embraces the commercial life as one worthy of living as she desires. Participation in this realm represents one of the best aspects of being in the world. Marion represents a sense of contentment with the existing state of affairs.
Over time, George develops a different perception of reality. He embraces a paradigm where he experiences discontent with a commercial state of being. What Marion sees as progress, George see as debilitation. One of the fundamental reasons Marion's personality and desire conflict with George's is because she does not embrace the sense of decay that George sees in the world.
I suffered, I suppose, from a sort of ennui of the imagination. I found myself without an object to hold my will together... Before that I had seen only the world and things in it, had sought them self-forgetful of all but my impulse. Now I found myself GROUPED with a system of appetites and satisfactions, with much work to do—and no desire, it seemed, left in me.
George struggles because after marriage he is unable to discover purpose in his life, as he lacks "an object to hold" his "will together." Marion does not suffer from this. She has found economic wealth and financial prosperity and this sustains her quite well. This difference in perception is where their conflict and eventual drifting apart lies. It is in this contrast in paradigm that Marion's personality and desires come into conflict with George's. Being able to see this difference is what contributes to their eventual separation.