It is easy to give up on your prodigal when they give you no reason to hope for reconciliation. But remember your faith is not in them, but the God who made them and knows all about them, you, and all the details of your situation. God in his infinite mercy allows us to participate in His work via prayer. Christ told the situation of a widow who petitioned a mean judge continually. She eventually got her justice. How much more will your Father God, who loves you and your marriage infinitely, response to your prayers in His time. He wants you to talk to Him!
Luke 18
Then Jesus told his disciples a parable to show them that they should always pray and not give up. He said: “In a certain town there was a judge who neither feared God nor cared about men. And there was a widow in that town who kept coming to him with the plea, ‘Grant me justice against my adversary.’
“For some time he refused. But finally he said to himself, ‘Even though I don’t fear God or care about men, yet because this widow keeps bothering me, I will see that she gets justice, so that she won’t eventually wear me out with her coming!’ “
And the Lord said, “Listen to what the unjust judge says.And will not God bring about justice for his chosen ones, who cry out to him day and night? Will he keep putting them off?I tell you, he will see that they get justice, and quickly. However, when the Son of Man comes, will he find faith on the earth?”