I'm a bit unclear as to what your precise question is. Do you have a round trip ticket booked already? If so, then you can tell them that you have your return ticket booked if they ask. Otherwise, tell them that you are there to VISIT your girlfriend. If you do not have a return ticket yet, tell them that you have not yet determined a specific date, but that you are willing and able to leave if necessary. Unless you get a specific exit date from the border agent, then you can stay the 6 months and then apply for an extension from inside Canada. You wouldn't have to use the return ticket home if you didn't have to. In terms of funds, it's entirely subject to the agent, but if you have no job or significant ties to your home country, and no return ticket, and cannot prove any resources to support yourself, you might have a tougher time at the border.