My guess is you're saying that your girlfriend/wife is menstruating ("that day") and she doesn't want to do anything with you, not even kissing? Am I understanding this correctly? And she's being mean and all?
Dude, during that time she's in a lot of discomfort/pain. Her abdomen's literally cramping and pushing out stuff (and depending on how her health is normally, the discomfort could get a lot worse for her. Women can end up in the hospital from the pain, it can get that bad). So yes, of course she's going to be mean and grumpy.
Be nice and understanding to her. Ask her how you can help her be more comfortable. She doesn't feel like going out? It's ok, just hang out at her place. I heard chocolate usually helps also, there's something in it that boosts your mood (actual chocolate though, not white chocolate). Get her food she wants. Nothing too spicy or cold though, those normally already irritate the guts, it'll make the cramps worse.
She may continue to be grumpy and mean during those days, but she'll remember you making the effort. She'll be nicer to you during other times.