Faithfulness can be described in many ways; adherence, ardor, constancy, dedication, deference, devotion, duty, faithfulness, fealty, fidelity, homage, honor, obedience, obligation, piety
Ruth - Chapter 1:16-17
16. But Ruth replied "Don't urge me to leave you or to turn back from you. Where you go, I will go and where you stay I will stay. Your people will be my people and your God my God.
17. Where you die I will die, and there I will be buried. May the Lord deal with me, be it ever so severely, if anything but death separates you and me."