When she gives up on you, it's obvious. 

1. She will not try to catch your attention.

2. She will not fight for you anymore. 

3. She won't reply your message as quickly anymore. 

4. She won't try to keep the conversation going anymore. 

5. She will not care anymore. 

6. She no longer get jealous. 

7. She no longer care if you care or not anymore.

8. She no longer goes to your profile and whine to people about how happy you're, talking to other girls. 

9. She will give up on trying to make you love her, because she finally realise that she deserves better. 

10. And you will miss her. Miss the way she cared about you. Miss the way she loved you. And you have lost her. 

So don't take any girls for granted, if you love her, let her know before she gives up.