There's no deficit of relationship advice for men on how to make your woman feel safe. There is far less advice for women on how to make their men feel safe. In order to open up, be vulnerable, and have the sort of intimacy that is the hallmark of a strong, long lasting relationship men need to feel safe.
Men are dying for a safe space to excise all their ghosts and clear out their closets. That place should be their intimate relationships. Unfortunately the idea of a vulnerable man, one who is comfortable opening up about his feelings, is one that isn't seen as "masculine" or in some cases desirable.
Women, your man will feel insufficient and unfulfilled if you don't offer him this safe space to explore and process his emotions, fears, needs, and wants. He looks to you to be a safe harbor in the storm and if you invalidate or belittle his emotional and vulnerable side, even unintentionally, he'll close up and you won't have access to that part of him again.
So, if you desire a strong, deeply intimate relationship, give your man the safe space he truly needs.