I think your action in your form is being triggered to reload itself. Have a look at this Demo http://jsfiddle.net/JuY9L/ Where I have changed the code of the form so that it returns an empty action.
HTML:
<div id="deviceready" data-role="page">
<div data-role="header">Header</div>
<div role="main" class="ui-content">
<form action="javascript:void(0);">
<label for="username">User name:</label>
<input name="username" id="username" value="" type="text" />
<label for="password">User name:</label>
<input name="password" id="password" value="" type="password" />
<button id="submit-login" class="ui-btn ui-shadow ui-corner-all ui-btn-icon-left ui-icon-user">Login</button>
</form>
</div>
<div data-role="footer">Footer</div>
</div>
<div id="formResults" data-role="page">
<div data-role="header">Header</div>
<div>Hello from success</div>
<div data-role="footer">Footer</div>
</div>