Backsliding is normal. It can be difficult to move beyond a severe betrayal. When that happens it helps to quickly acknowledge a partner’s pain/frustration AND try to steer the conversation to more productive ground. Say something like, “I see you’re upset. What I did was wrong and I’m sorry about what happened. What can I do right now to make things better?”
The important point is not to get angry or become defensive at your partner for backsliding. When such conversations consistently slide into mutual contempt and criticism that is often the kiss of death.
It also helps to be proactive and plan an event or activity with your partner that you both enjoy doing and haven’t done before. Making a commitment (investment) to doing something novel can help couples regain positive feelings, closeness, and intimacy. Planning a weekend getaway, taking a class together, volunteering in your community, adopting a pet—anything that brings you both enjoyment and is novel can do wonders for a relationship.