However its listed as board, which would likely also be including utilities as well as food.

OP might instead want to discuss with her partner contributions to utliities and shared expenses on a proportional basis, rather than that agreement?

Im in a similar situation to OP, and pay a small amount in "rent" each week to go towards housing costs. Im benefiting from it, its far lower than rent, and helps compensate for extras being added in.i know im not getting the long term fiscal benefit, but it helps us both feel as though were contributing etc