what do you do if the person you are with doesn't know if they love
you but they still want to keep dating you?

Aww. Thats a nice question. I am going through that right now. Give
them their space, give them a chance to show commitment, and keep
hopes high! :)

Sounds like they don't want to make a decision.  Make it for them. 
Move on.  They know where you are.

Without knowing how much money is being spent on dates, or what sexual
activity is involved, it is hard to answer. But, if a lot of money is
involved, or a lot of sex, that pretty well explains why the desire to
keep on dating.  Think it over vdery carefully before investing more
time on this person if you consider marriage in your future.

You are a place holder until this person finds someone else.

get a backup just in case.

You haven't said that you are hopelessly in love him/her.  Lots of
(most?) people date with only a loose commitment to the future.