Aim of the study:
The aim of the study was to adapt and validate the Polish version of the Relational Mindfulness Measure (RMM) and to examine its psychometric properties in the context of relational distress following partner infidelity.

Subject or material and methods:
The study was conducted on two independent samples of adults who had experienced partner infidelity and remained in the relationship (Sample 1: N = 187; Sample 2: N = 404). The factorial structure of the scale was examined using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). Reliability was assessed using Cronbach’s α coefficient, while construct validity was evaluated through correlations with dispositional mindfulness (FFMQ-SF) and relationship satisfaction (RAS). Group differences were analyzed using ANOVA.

Results:
CFA supported a one-factor model after allowing a residual correlation between Items 3 and 4 (CFI = .995, TLI = .986, RMSEA = .082, SRMR = .039). Internal consistency was satisfactory (α = .78). Relational mindfulness was not significantly associated with dispositional mindfulness but showed a small negative correlation with relationship satisfaction (r = –.178, p < .001). Additionally, significant differences were observed depending on the time elapsed since infidelity and its disclosure.

Discussion:
The findings suggest that relational mindfulness may capture context-specific aspects of mindful awareness in intimate relationships and may operate differently under conditions of relational distress.

Conclusions:
The Polish version of the RMM demonstrates satisfactory psychometric properties and may be a useful tool for research and clinical practice in romantic relationships.