Final answer:
The main similarity between the men Edna had dated before she met Mr. Pontellier is their wealth and belonging to the upper class. One major character who fits into this category is Robert Lebrun.
Step-by-step explanation:
The main similarity between the men Edna had dated before she met Mr. Pontellier is that they were all wealthy and belonged to the upper class of society. They were able to provide Edna with a comfortable and luxurious lifestyle. One major character who fits into this category is Robert Lebrun. He is a wealthy, well-traveled young man who is part of the upper-class society in Grand Isle.
Hence, the primary resemblance between Edna's previous romantic partners and Mr. Pontellier was their affluence and social status.