How to build relationships

I have a Korean coworker (female). We work in Western Europe. She is new here and we are of the same age. She is kinda pretty and cute. I asked her for a coffee and she agreed. And it was the most boring coffee chat I’ve ever had. I tried to ask questions and engage her, but her answer were always short and she didn’t attempt to keep dialog. When we meet with a team she always sits with a poker face and doesn’t engage in conversations. Is it cultural thing or just her? I wanna get close with her but she is..what should I do to make her comfortable?