My suggestions are,
Make a nice hot bubble bath for your loved one, light a few candles, turn down the lights, add some aromatic oils and maybe some flower pettles and your good to go!
Perfect for her/him or you both to enjoy as a couple.
Next, go to your local supermarket and buy. There valentines meal. This usually includes a main a side a dessert an a bottle of wine.
Cook that in the oven.
Set the table, add a table cloth, some rose pettles, knives am. Forks, and a wine glass.
Then, dim the lights and light some candles.
Turn some smooth music on.
And for an added extra, you could get your girl a new dress to wear for the night, lay it on your bed and when she gets out the bath, she will read a note telling her to put this on and meet you down stairs.
This she will think is so cute and romantic, even though it hasn't cost a bomb. She will appreciate all the thought that has gone into it.