Should I treat my gf just as a sex object?

[Bombom]

I gave her my love, my best. I plan to travel with her to another countries. I save up my money for her. Despite all that I have done, she is not very grateful to me. Recently, she got admitted to a hospital because of a kidney infection. I travelled to another part of the country immediately just to see her that night. She had been staying there for 6 days. I asked her if I should travel to see her yesterday morning, she said she didn't want it and didn't like it. She said I overly reacted but the reason I asked her was because she told me the seriousness her illness.

She also keep our relationship as a secret on facebook. I am thinking she might have something else going on with her. I used to give her my best but should I just use her for sex now? My male friend told me I could just use her for sex but not as a gf.