Often a woman feel it is better to keep emotions in check early in a relationship simply because she fears she will be rejected if she seems too emotional.
It is often true that men will drop an overly emotional woman, especially if one of those emotions is jealousy, or anger over little things.
They want to be perceived as relaxed, open and easy going.
But this often backfires when the emotional side emerges and she is seen as having been dishonest.
It is always better to be yourself from the start.