No one can predict any relationship duration by making their own assumptions, because every partner and every relationship is different.
But many times it is commonly seen that, when a partner ignore another partner and do not give attention, then it means he or she is no more interested in the relationship. That directly shows that person need a break.
But wait, not every time we can assume this same. Sometimes many partners get responsibilities of children, responsibilities of earning money to support their family or many family problems, in this such a pressure, obviously a partner get less time and indirectly it leads to lack of attention for another person.
So, i have told you both the sides, where sometimes people ignore and give lack of attention because he or she no longer want to continue the relationship. But on other hand, many times it is seen after marriage partner get responsibilities and pressure, that does not mean the partner want to end the relationship.
Lack of attention sometimes results in end of relationship and sometimes not. Many partners really want to end the relationship, that is why they give lack of attention. But some partners have responsibilities of family, so that is why they give less time to partner.