If you find it difficult to share your past experiences, ask yourself why you are reluctant to open up. Getting to the root of the reluctance is key.
Before you talk to your partner about something difficult, find the right words to express it first. Until you can verbalize it, it remains unknown to you and to your partner.
If you do not feel safe enough to talk through these issues, consider journaling, or talking with a counsellor until you are clear about how you are feeling.
When you decide to open up, start by taking small steps to test the waters first.
The more you practice and see that you can do it, the easier it will get for you to open up.
Practicing vulnerability includes knowing your vulnerability and expressing your real thoughts instead of what you think your thoughts and wants should be.
Consider communicating to your partner that you are having a hard time opening up and may need extra time.
It's good to be honest about what you need or want from your partner after you open up.
Let them know that you do not need to be fixed. The purpose is to connect.
... before you talk about something important.
Invite your partner to sit down with you, without distractions, and let them know that you want to talk to them. Let them know how you feel and that you find it important to feel emotionally safe with them.