Hi Katie and Welcome!
The fact that you are reaching out and asking is a great of something you significant other (SO) will need. That is support.
You both will. This can be a complicated issue and like many of us your SO has had no one to speak to, or dare tell about this part of their persona.
Be patient, be supportive and ask questions. They may not be able to answer every thing but this group if full of wonderful “ladies” who are willing to help at every turn.
Wonderful you are supportive.
Love and hugs to you both!