I don’t like to say this, but if you don’t get a handle over your jealousy, you highly risk losing this relationship.

Firstly, you should really take the time to get to the root of your jealousy rather than just telling yourself not to be jealous. You very well may be right when you stated that your previous [wrongful] actions play a role in this. Did something happen in previous relationships that caused you to feel jealous? Are you jealous because he has something going on that you aren’t a part of? Would you feel this way if his actions were with a male friend over a female friend? Take some time to really mediate on this. Find the root and come to peace with things otherwise you will risk hurting your boyfriend, who is an innocent in all of this.

As to this girl not responding back, I’m not entirely surprised. If you really want to get to know this girl, you and your boyfriend should set up a time to meet with her, but I would do it in a setting where there is a group so that it’s not threatening to her or seems like you’re trying to single her out. When you do meet her, have the mindset that you would meeting your boyfriend’s male friends or family, then judge your thoughts after you see their interactions, but don’t read into anything too deeply.

One last thing. Do you have any hobbies or activities you do on your own? You mentioned your boyfriend does coffee art, and him and this girl have a connection through their profession. If you don’t, it’s really good to have something that is your deal. Doing something apart from your relationship is very healthy and could also help with your confidence, which could help with your jealousy. Just a thought.

I hope this helps!