Lack of pregnancy sadness, please help

Okay so about four months ago me and my Mrs decided we'd start trying for a baby. But she hasn't got pregnant yet and she gets pretty upset every time she cramps from her period getting so close, and then she periods, and it's really getting her down and I feel like I'm not doing a good enough job getting her pregnant. Anyone got any tips or anything I can say to make her feel better (and make me feel better by proxy)?