It's essential to remember that relationships can be complex and varied, and the reasons for someone's behavior may differ from one person to another. However, I can offer some possible explanations for this behavior:
Emotional attachment: Your boyfriend may still have emotional attachments or unresolved feelings towards his ex. Blocking her might feel like cutting off that connection completely, which he may not be ready to do.
Guilt or fear of confrontation: Blocking someone, especially an ex-partner, might feel like an aggressive action or could make him feel guilty. On the other hand, he may not have the same reservations about blocking you during an argument, as it can be seen as a temporary measure to avoid further conflict.
Different coping mechanisms: People handle emotions and conflicts differently. Blocking you during fights could be his way of creating space to cool down, while he might not feel the need to do the same with his ex.
Communication issues: It's possible that there might be communication issues between you and your boyfriend. Blocking you during arguments could be a sign of ineffective communication or a desire to avoid discussing certain topics.
Trust and insecurity: If your boyfriend feels insecure about the relationship or lacks trust, he may see blocking you as a way to protect himself or gain some sense of control.
History with ex-partner: Depending on the history and dynamics of the relationship with his ex, he might have reasons for keeping her in his life to some extent. It could be related to shared responsibilities, mutual friends, or even unresolved issues.
Remember, it's essential to have open and honest communication in a relationship. If you feel confused or concerned about his behavior, it's best to have a calm and respectful conversation with your boyfriend to understand his perspective and express your feelings. Healthy relationships require understanding, empathy, and effective communication from both partners. If issues persist and impact your emotional well-being, seeking support from a relationship counselor might be beneficial.