Do people's Big Five traits change over time?

Yes, slowly. Over 10 years, neuroticism typically decreases (people get more emotional stability), openness decreases slightly (less novelty-seeking), and conscientiousness increases (more responsible). These changes usually strengthen relationships—people get more stable and reliable with age.

What changes incompatible couples over time?

Values often diverge (one wants kids at 35 but not at 45; priorities shift). Personality becomes more pronounced (introverts more introverted, extroverts more extroverted). If change is parallel (you both grow similarly), compatibility strengthens. If change diverges (you value different things at 40 vs 30), incompatibility emerges.

Should we stay compatible as we change?

If both partners change, yes. If one person stays static and the other grows significantly, incompatibility can develop. The couple question: are you growing together or apart? Regular check-ins ("Who am I now? Who are you?") keep you aligned despite change.