Letting go of how anyone else will view this, if you do decide to part ways, is rather important, because it does not matter, not one bit, not for a second. Worrying about it at all is a complete waste of your time.
That guilt is misplaced. They are not living your life for you (or hers for that matter). What makes you think this anyway? Is it something that might have come up in conversation with her?
I'm just going to be blunt here (not meant to be harsh) but it sounds like you would just like to go your separate way from her.
You have only been dating a year. That is a good amount of time to get to know someone quite well and you have. You know this is not a romantic relationship that you want, you are not happy nor are you comfortable in this role you have been given.
Her brushing off your concerns is one of many red flags here. Basically you are saying, hey this part of our relationship isn't working so well for me and the response is, basically, get used to it?
It's not pleasant, it's not easy but it is probably the best thing for you to do. You can muck around with boundaries and trying to change the dynamic but that's kind of a waste of time. It is what it is.
Put aside what anyone else will think and perhaps think about looking out for yourself. If you don't, who do you think will?