Talking stage stop texting me and being communicative

I’ve know this girl a long time but we’ve never interacted till 5 months ago and started a talking stage 3 months after, everything was going fantastic and we got intimate till the point I am extremely attached to her. All went down when her ex boyfriend of 3 years came to visit and she stopped being responsive and stopped communicating as she used to, her ex left to go back to New York but since then this has been occurring. any recommendations and advices and what to do in these situations?