Only you and/or her can answer that. There are too many missing details that are probably very personal that we aren't aware of.

You are very new to this site and these 3 posts are the only ones we have to go on as far as knowing anything about you.

I highly doubt that after two years together the "shift" came quickly. Something[s] led up to her "dumping" you. I think the straw that broke her back came in the week between talking about marriage and the next week when she "dumped" you. Start there and work your way back through the days, weeks and years and see if you can find a common denominator.

Something spooked her and I have a feeling you can figure it out if you don't already know.

Good Luck!

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Minds are like parachutes. They only work when they are open.

~Thomas Dewar~