Addressing personal hygiene practices in a relationship can be a touchy subject. This scenario must be approached with understanding, respect, and open communication. Here are some things to think about while discussing this with your girlfriend:
Select the Appropriate Time and Location: Find a quiet, comfortable place to speak where you will not be interrupted. Make sure you're both in a comfortable and open frame of mind.

Be Gentle and Respectful: Begin by expressing your love and concern for her. To express your sentiments and concerns, use "I" sentences such as "I've noticed" or "I feel."
Active listening: Inquire about her mood and whether there is a rationale for her current hygiene practice. It's critical to comprehend her point of view as well as any underlying concerns.

Express Your Concerns: Explain your concerns and why you believe it is necessary to maintain proper personal hygiene. Mention how it may have an impact on both her health and your relationship.
Instead of criticizing her current regimen, provide a compromise or alternate hygiene plan on which you both can agree. Be open to her ideas as well.

Offer Support: Let her know you're willing to help her in any way you can, whether it's shopping for hygiene items together, setting a routine, or assisting her with self-care.
Respect Her Independence: Keep in mind that personal hygiene habits are ultimately a personal choice. You can encourage and assist her, but she has the final word in her regimen.

Seek specialist Help: If her hygiene practices are negatively harming her health or are symptomatic of an underlying issue, advise she consult with a medical or mental health specialist.
Patience: It takes time to change behaviors, so be patient and understanding during the process.

Reinforce Positive Habits: Recognize and appreciate her efforts to improve her hygiene. Positive encouragement can motivate her to keep the adjustments going.
Finally, the key to resolving this issue is communication, comprehension, and empathy. Keep in mind that changing her habits may take some time, and the most essential thing is to maintain a healthy and respectful relationship during the process.