It's essential to be cautious about making definitive assumptions about someone's motives or actions without knowing the full context. However, based on the information you've provided, it's possible that your narcissistic boyfriend could be engaging in manipulative behavior to elicit a jealous reaction from you.
Narcissists often seek attention, admiration, and control over others. Creating situations that provoke jealousy is one way they may try to gain a sense of power and influence over their partners. By making you jealous, they may be attempting to make you feel more emotionally invested in the relationship or to create a sense of competition for their affection.
Additionally, some narcissists may use jealousy as a tactic to distract you from other issues in the relationship or to keep you on edge, making it easier for them to maintain control over you.
Regarding the issue of having other sources of supply, narcissists often crave constant validation and attention from others, so it's not uncommon for them to have multiple targets or "supply sources." However, it's important to remember that each individual is unique, and the reasons for their behavior can vary.
Regardless of the reasons behind your boyfriend's actions, it's crucial to recognize manipulative behavior and prioritize your emotional well-being. Healthy relationships are built on trust, respect, and open communication, not on mind games and manipulation. If you find that this behavior is causing you distress, it may be worth considering seeking support from friends, family, or a therapist to help you navigate the situation and make decisions that are in your best interest.