Selfishness is already harming the marriage. Neither is seeking a way to get the other to heaven, but instead they both are turning to their wants and desires over the marriage and over Gods plan. Since the consequence of sin is death, they will experience a consequence. It could be the end (end = death) of their compromising, the end of great conjugal loving ( BCP’s decrease woman’s libedo, verse toniest may too), it may be the end of growing a family, the end of maintaining the family, the end of turning to God (if the catholic is disobedient to God), the beggining of the end of the marriage, the end of …
It’s a shame when a married couple turns from team to competitors.