Dear friend and sister,
In praying for this woman and man and his spouse, you are doing what God desires of you.
It was wrong of the person to spread gossip, and if is how the friend is handling the allegation, then scandal is probably immanent, and lives and relationships potentially destroyed.
You awareness of the problem is relevant only in that it gives you the opportunity and mission to pray for these people.
I thank God that you are in a position to be able to welcome the grace to pray for these people. God is counting on you, and now us, to help you pray for them…so as usual, God is bringing good out of what is not good, touching the sin of adultery and the sin of gosspi with His transforming love.
And we can’t really be surprised even at the sin of an upright person.
Even though they had spent three years constantly in His presence, seeing His goodness, observing His miracles, and three of them, His transfiguration, the disciples ran out on Jesus when He needed them most. His closest three fell asleep when He requested their prayers and company; and all their lives they couldn’t get back that time during His torture and agonized death, they abandoned Him, except John.
That is a human, but a horrible thing.
Remember that Jesus said, "If you deny me before men, I will deny you before My Father in Heaven. [Mark 8:38] Well His chosen disciples did deny Jesus before men, one by perfidious betrayal of Jesus to His protagonists, but the others by their actions, and Peter directly. Those were serious sins of mostly good men. If it happened to the best of men, it can happen to any person, potentially. The apostles (bar Judas) didn’t remain in their sins of betrayal, and please God this accused couple will not remain in their perceived sin.
God grant that our prayers for all involved will bear fruit.