You cannot force your partner into therapy. However, you can get help for yourself, and with long-term effort, you could convince your partner to get help over time, with increased trust, consistency, and a genuine show for concern.
For instance, you could say, “I’m still here. I wouldn’t be if I didn’t care.”
If you are not strong in yourself, having a person in your life with BPD can make you feel like your life and identity are disappearing as you are trying to meet all the needs and demands of your partner. You will most likely have a difficult time maintaining your health if you have issues going on, such as depression, anxiety, low self-esteem, or substance abuse.
Self-care is essential. Being able to maintain strong, definitive, consistent boundaries is important, and getting the support of a mental health counselor or clinical psychologist will help you maintain your health so you can be there for your loved one in the most productive manner possible.