Loyal Landlords, LLC owns and manages a large commercial storefront. Home Hardware, Inc. agrees to lease the storefront for six years. Under the lease, Home Hardware, Inc. is obligated to pay all of the utility costs. Three years into the lease term, Home Hardware, Inc. asks Loyal Landlords, LLC to modify the lease to split the utility costs equally between the parties. Loyal Landlords, LLC agrees, but later decides it does not want to share the costs and refuses to make any utilities payments. Is Loyal Landlords, LLC bound to its agreement to share the utility costs? Why or why not?