Personality traits are highly stable in persons over 25 years old to 45 years old.

"Personality trait change in adulthood." Current Directions in Psychological Science, 17, 31-35.

Roberts, B. W. & Mroczek, D. (2008).

http://www.psych.illinois.edu/~broberts/Roberts%20&%20Mroczek,%202008.pdf

Personality traits are defined as the relatively enduring patterns of thoughts, feelings, and behaviors that distinguish individuals from one another.

Graphs showing cumulative change across the life course are shown in Figure 1.

The findings were organized according to a modified Big Five framework (e.g., Extraversion, Agreeableness, Conscientiousness, Emotional Stability, and Openness to Experience) in which the domain of Extraversion was further divided into the subdomains of social vitality (e.g., gregariousness) and social dominance (e.g., assertiveness).

The results showed that people became more socially dominant over time, especially in young adulthood. [Cumulative dValue change less than 0.3 for persons over 25 years old to 45 years old]

Social vitality showed small increases in adolescence and then small decreases late in life.[Cumulative dValue change 0.0 for persons over 25 years old to 45 years old]

Although much of the change on agreeableness was positive, the increase was only statistically significant in old age. [Cumulative dValue change less than 0.2 for persons over 25 years old to 45 years old]

People showed little change on conscientiousness in adolescence but then showed remarkable gains in young adulthood and midlife. [Cumulative dValue change less than 0.3 for persons over 25 years old to 45 years old]

Emotional stability showed steady increases through midlife. [Cumulative dValue change less than 0.3 for persons over 25 years old to 45 years old]

Finally, individuals demonstrated gains in openness to experience in adolescence and then equivalent declines in old age. [Cumulative dValue change less than 0.1 for persons over 25 years old to 45 years old]

Personality traits are highly stable in persons over 25 years old to 45 years old (the group of persons who could be most interested in serious online dating)