Supporting a girlfriend who's feeling sad but not admitting it requires sensitivity and patience: 1. Pay attention to non-verbal cues that might indicate sadness. 2. Create a safe, non-judgmental space for her to express her feelings. 3. Offer your presence and support without pressuring her to talk. 4. Engage in activities she enjoys to help lift her mood. 5. Express your love and appreciation for her regularly. 6. Be patient and give her time to open up when she's ready. 7. Encourage healthy habits like exercise and proper sleep. 8. Offer to listen if she wants to talk, without trying to "fix" everything. 9. Suggest professional help if her sadness seems prolonged or severe. 10. Take care of your own emotional well-being to be better equipped to support her.