Donna, a family therapist, is explaining to her friend Betty, a 40 year-old African American female and Vice President at a large bank, that Betty is having difficulty finding a mate due to the marriage squeeze. In simple terms, What Donna means is that .

There is an imbalance in the ratio of men who are eligible for marriage to women who are eligible for marriage    

Explanation:

Marriage squeeze: The term marriage squeeze is described as a demographic imbalance whereby the number of different "potential brides" is not considered as equal to the number of "potential grooms". When every individual doesn't get an opportunity to marry someone then a few people will be deliberately squeezed out from the "marriage market" and won't be able to get to marry.

As per the question, in simpler terms, what Donna means is that imbalance in the ratio of male and female occurred.

just don't strip down in public lol