This question cannot be answered with a simple yes or a no. Typically, adultery will not be relevant to a child custody case as long as the children are completely unaware of the affair and it has not touched their lives in any way.
However, Judges will definitely examine how the new relationship has impacted children and it this could sway their decision when it comes to custody. With respect to children, a Judge’s role is to decide what is in their “best interest”. This is a very broad phrase and it gives the judges great discretion as to what they consider when deciding custody.
Typically, Judges strongly frown upon children being introduced to a parent’s new romantic partner. Most of the Judges in Texas tend to believe that divorce is hard enough on children without introducing a new girlfriend or boyfriend into the picture. When this is a concern, a Judge may order a “morality clause” which can prevent a parent from introducing the child to their new romantic partner and/or prohibit the parent from having the romantic partner spend the night with him or her while the children are present.
As a San Antonio Divorce Attorney, I typically advise my clients to wait on introducing their children to a new boyfriend or girlfriend until the divorce is finalized. This is generally best for children and for my client’s cases.