She sounds very withdrawn. This is alright for some, but clearly not for you. You prefer affection and openness and you should probably be with someone more like you. But if you really want to make this work you really need to communicate with her. Don't allow her to ruin the night. It's not your conversation that's doing it, its her! Say "listen, we need to have a serious conversation about our relationship whether you like it or not." Don't let her get up and leave, don't let her get angry, because that's not what you're doing. Explain to her that it's not a fight, it's just a conversation that is essential to the success of your relationship, and that if she really does want it to work, she will have this conversation with you.
May the wind always be at your back and the sun upon your face. And may the winds of destiny carry you aloft to dance with the stars