If your girlfriend is completely ignoring you, you might not be able to get in touch with her via phone or in person. If you know she is still getting your texts, you might try sending her a message that expresses your concern and asks her to meet up and talk. Example: “You haven't been responding to my texts lately. When that happens, I feel hurt and wonder if you're still happy in our relationship. Can we meet up and talk?” If you know her schedule, you might even suggest a day and time when she is usually free, which could make it easier to get her to commit to meeting up. Skip this step if your girlfriend responds to you via text or phone. If you can't get in touch with her via text or phone, but you know that she is still okay (i.e. hanging out with friends, posting to social media), you might try sending her a message that lays out your feelings and concerns via her Facebook inbox or an email address.  If you choose to send an email/private message, be sensitive to your tone. Write a draft, then re-read it after you've had a good night's sleep. Make sure that it isn't mean or disrespectful. Be specific. Provide concrete examples of what she does and how you feel. Be sure to word it in a way that isn't accusatory: “When we were at that party on Saturday, you spent the whole night talking to other people. We didn't get a chance to talk at all, and you left without saying goodbye, even though we were sitting across from each other in the same room. When you did that, I felt hurt. I wasn't sure if I had done something wrong. I am worried about you, and I am worried about us. I would like to get together in person and talk this through. Or, if you're uncomfortable with that, I am also open to communicating via email for now.”  Before sending your email, try to put yourself in her shoes as you give it a final read. Think about how it might sound to her, and how she might react, and edit it to ensure that you are sharing your thoughts and feelings in the most effective way possible. If she understands your...

TL;DR in Indonesian:
Rencanakan sebuah kencan untuk berbicara empat mata. Kirimkan sebuah surel atau pesan pribadi. Gunakan bahasa tubuh yang menunjukkan empati. Tunjukkan pemikiran dan perasaan Anda menggunakan komunikasi tanpa kekerasan. Tanyakan tentang dirinya. Tanyakan apa yang ia butuhkan. Jadilah pendengar yang aktif.