There is a story called 'When the boat comes to the bridgehead, it will cross naturally.' It is written very figuratively. I don't understand it. Who can help explain what it means?

On the day his son was born, the sky suddenly changed and the village was flooded.
His father had made the mattress high in the house overnight. She still remembered that when she gave birth, she looked up at the roof beam and under her body was running water.
The little fellow had handsome features. The couple liked him so much that they could not close their mouths every day. They gave him a nickname, Boat.
He hoped that he would be able to live a life without fear of the great waves and have smooth sailing.
When Chuan 'er was five years old, his father suddenly fell seriously ill. The village doctor could not explain why, but he could not stop coughing.
Before they left, his father held her hand and sweat dripped down his palm.
Our family has very few descendants. By Chuan-er's generation, he's already the only heir for five generations. Raise him and teach him well. After saying this, his father really left.
It was said that there were many disputes in front of a widow's door. She never showed her face in public and could not look after her husband. Raising her son had become her life.
Day by day, year by year, the boat grew taller, and the edges of his face became more and more distinct. He looked very much like his father.
She looked at her son's face and often shed tears. She didn't know if it was because she was thinking of an old friend or herself.
When Chuan 'er was eighteen years old, she asked her son if he had any girls he liked. If he did, she would ask someone to talk to him.
His son shook his head and said that he had to serve his mother well. It was not time for him to get married yet.
Wouldn't she be able to serve her mother better if she married a wife? Silly child, she smiled.
Mother, actually, actually I don't want to get married. I, I like men.
The words came out of Chuan 'er's mouth clearly. She looked at her son, but it was as if she had never recognized him.
The news was like a bolt from the blue. It instantly reminded her of many things. Her husband's trust rang in her ears again.
'Which lifetime did I commit this sin?' She smiled bitterly in her heart.
Child, let me take you somewhere. She still opened her mouth.
The two of them went out and walked for a long distance before arriving at a stone bridge.
Let's stand at the bridgehead for a while. she whispered to her son.
His son obediently walked over and stood at the bridgehead, listening to the breeze and the fine water.
In the time it took for half an incense stick to burn, the son turned around and looked at his mother, lowering his head in embarrassment.
Mother, I want to get married, with a woman.
She smiled, and the huge rock in her heart finally fell to the ground.
On the way back, his son kept asking,"Mother, what's going on?"
She stopped and said," When I was young, the old man told me that things will work out when they come to it."

Answer 1

The bridge will cross when it comes to it is a common literary allusion that is often used to describe self-adjustment and self-liberation in a difficult situation.

The meaning of this sentence was that when the ship sailed to the other end of the bridge, there was no need to worry about the ship turning back because the road had already extended forward and the bridge would naturally appear. This metaphor means that when we encounter difficulties or challenges, we should not lose confidence or be impatient because things will often develop naturally in a better direction.

This allusion was often used to encourage people to have patience and confidence in the face of pressure and difficulties, to stick to their beliefs and goals, and to believe that the future would be better.