What people say generally accounts for 20-50% of what we communicate, the rest is down to body language. When a relationship is going through difficulties couples tend to talk less so it’s really important to be more aware of how you communicate non-verbally and to try to keep talking honestly.
facial expression -not smiling can strongly express negative feelings - obvious but you might not be aware you’re doing it! Poor eye contact communicates mistrust/untrustworthiness whether you intend it or not.
body language - folding your arms is a sign of defence/low receptiveness to what your partner says; turning your back to continue other tasks signals not listening.
touch - early in a relationship affectionate touch is common, introducing it again eg putting your arm around your partner, touching their hand/arm communicates caring. Touch can also raise levels of oxytocin in the brain - also known as the 'cuddle hormone' it can increase a sense of trust and intimacy and strengthen a relationship.