Supervised Fine-tuning (SFT) and preference optimization (PO) are key methods for enhancing language models and aligning them with human preferences. However, scaling preference datasets for PO training is challenging, leading AI customer support systems to rely on SFT. To address this, we propose the Sentiment-guided Automatic Generation of Preference Datasets (Sentimatic) methodology to automatically generate customer preference datasets without human intervention using a publicly available dataset constructed for SFT. Our approach classifies responses by sentiment, fine-tunes models on them, and applies advanced sampling and evaluation techniques to ensure diversity and quality. Ultimately, we generated 1,174 customer preference datasets based on 357 test datasets, and through experiments, we confirmed that the AI customer support system trained on these datasets is capable of carefully considering customer emotions and generating professional and appropriate responses.