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

Material and Methods:
Two independent samples comprised adults who had experienced partner infidelity and remained in the relationship (Sample 1: N = 187; Sample 2: N = 404). Factor structure was examined using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). Reliability was assessed using Cronbach’s α, and construct validity was examined through correlations with dispositional mindfulness (FFMQ-SF) and relationship satisfaction (RAS). Group differences were analysed using ANOVA.

Results:
CFA supported a one-factor model after a residual correlation was added between items 3 and 4 (CFI = 0.995, TLI = 0.986, RMSEA = 0.082, SRMR = 0.039). Internal consistency was satisfactory (α = 0.78). RMM scores were not significantly associated with dispositional mindfulness but showed a small negative correlation with relationship satisfaction (r = −0.178, p < 0.001). Scores also differed by time since infidelity and its disclosure

Conclusions:
The findings suggest that relational mindfulness may capture aspects of awareness specific to intimate relationships and may operate differently under conditions of relationship distress.The Polish RMM showed promising structural and reliability characteristics, although its construct validity and potential clinical use require further investigation