Talking to your girlfriend face-to-face is an excellent way to gain a better understanding of her. Sometimes you can't pick up on things like voice intonation or sarcasm through text message, and you can't look at her body language when you're talking to her over the phone. Set some time aside to speak with her openly and honestly about anything. It could be small-talk about how your day went, or it can be deeper and more meaningful conversations about what makes you both happy.  You can start the conversation by saying something like, "Hey I wanted to talk to you about where we are going in the relationship. Do you have time right now?" Talking about things that you feel vulnerable about will encourage your girlfriend to do the same. This can bring you both closer together. For example, you could talk about your first childhood memories, a favorite family traditions, worst fears, or lifelong dreams. Active listening engages both people deeper in a conversation and will make your girlfriend appreciate you more. To practice active listening, concentrate on what she is saying without interrupting. Do not judge her or criticize her if she tells you something embarrassing, because it could prevent her from telling you things in the future. Paraphrase things that she says and ask specific questions about what she is talking about. Try to give advice that helps her and is in her best interests if she seems like she wants it.  To paraphrase, say something like "So what you're saying is that she was acting immature." Sometimes people just want someone to talk to and not to receive advice or judgment. Wait for her to ask you for your opinion before trying to help. Talking to someone is not the only form of communication that exists in a relationship. Nonverbal communication is also incredibly important. If you pay attention to your girlfriend's body language, you'll be able to determine how they feel at the moment. Crossed arms may mean they feel defensive or closed off and may mean that they aren't interested in what...

TL;DR in Indonesian:
Berkomunikasilah dengan kejujuran dan keterbukaan. Belajarlah mendengar secara aktif. Perhatikan komunikasi nonverbal saat berinteraksi. Jangan membahas isu personal jika sedang marah. Jangan membentak atau mengamuk saat bertengkar. Terapkan aturan yang adil saat bertengkar.