The physical mind will influence you to believe that the 'problem' is actually outside of you (external) - i.e. your boyfriend's behavior and what other women are doing... It will influence you to focus your attention on the external factors in your life experience... This leads to attempts to exercise control over the external circumstances in order to try and 'protect' yourself - which will never succeed and will invariably fail...

The heart of the matter is an internal 'issue' that resulted from earlier emotionally challenging life experiences which left an 'impression' upon your state of being... Impression meaning the unresolved/unprocessed emotional energy stemming from those life experiences that has been retained (held onto) and is waiting to be healed (and released). This is what causes your sensitivity and feelings of insecurity/vulnerability/fear... Being an internal 'issue', the good news here is that you absolutely have the ability to influence and exercise control over your state of being. So you see you have to make an effort to shift your focus/attention & conscious energy away from the surface-level external circumstances which trigger your sensitivity (this is the symptom) - and instead direct your focus/attention and conscious energy inwardly so that you can conduct the necessarily introspection and inner-work to process what's still unresolved inside you (the cause) and eventually heal yourself! This is an important realization because think of how much time and conscious energy has previously been spent on worrying about the external circumstances that were making you feel uncomfortable while neglecting the root cause of the emotional sensitivity? You don't have to subject yourself to doing this anymore...

Realize that these current feelings are really about you (your internal condition) and not truly about what's currently going on 'out there' (external to you)... In terms of working towards your healing - you may find yourself revisiting and reflecting upon those particular earlier life experiences which had the greatest emotional impact on your state of being. There is emotional energy tied to those experiences which still needs to surface so that it can be consciously acknowledged and fully processed then released. The 'wounding' has to eventually be exposed (and no longer pushed away / suppressed) so that it can finally be healed. Are there perhaps any individuals that you are ready to bring yourself to forgive (in your own mind) so that you can part ways with the emotional material/energy associated with those individuals? Is it time for you to identify some new ways of perceiving your past experiences which will bring about a change in your former mental/emotional reaction to those experiences? These are rhetorical questions that do not need to be answered here - however important notions to consider. Journaling about your most sensitive emotions/feelings could prove to be very therapeutic/beneficial over the long term (this enables you to consciously connect with what's stored inside you). Exploring relevant self-help books/materials/videos could be helpful as well. Routinely remind yourself of the 'symptom' and 'root cause' analogy so that you can stop yourself from being distracted by the surface-level external circumstances which are merely 'reminders' for you that there is additional inner-work to be conducted and healing that needs to be brought about...