I don't have access to specific individuals' thoughts or intentions, so I can't say with certainty why your ex-partner acted the way he did. However, I can provide some possible explanations based on general knowledge about relationships and Borderline Personality Disorder (BPD).
Fear of Abandonment: People with BPD often struggle with intense fears of abandonment. While your ex-partner may have expressed a desire for a future together, he might have been afraid of committing to a real relationship due to the fear of being abandoned or rejected in the future.
Idealization and Devaluation: Individuals with BPD may experience rapid shifts in their feelings about others. They can initially idealize someone (putting them on a pedestal, expressing love and commitment) but then quickly switch to devaluing them (pushing them away, expressing anger or withdrawal). This emotional instability can lead to inconsistent behavior.
Impulsivity: BPD can be associated with impulsive behavior, which may lead to sudden changes in feelings or decisions. Your ex-partner might have been swept up in the emotions of the moment when expressing his desire to marry and have kids, but then later regretted or doubted those feelings.
Memory Distortions: Memory problems can be associated with BPD. It's possible that your ex-partner genuinely doesn't remember what he said or did during certain episodes due to dissociation or other cognitive issues related to the disorder.
Using Defense Mechanisms: Sometimes, individuals with BPD may use defense mechanisms, such as denial or projection, to cope with difficult emotions or situations. Claiming not to remember or denying what was said could be a way to protect himself from facing the complexities of the relationship.
Difficulty with Intimacy: People with BPD may have challenges with intimacy and trusting others, making it difficult for them to fully commit to a serious relationship, even if they express a desire for one.
It's essential to remember that BPD affects individuals differently, and not all people with the condition will exhibit the same behaviors. If you find yourself in a situation where your emotions are being toyed with or if you feel used in any way, it's crucial to prioritize your own well-being. Healthy relationships are built on trust, communication, and mutual respect. If you're dealing with a partner who is inconsistent, emotionally unavailable, or causing you distress, it may be necessary to seek support from friends, family, or a mental health professional. They can help you navigate these complex emotional situations and provide guidance on making decisions that are best for you.