In this case, it may be acceptable to have kids at a later age; in addition, there could be other related concerns not mentioned in the comment (a lot of information is lost when writing about something online), which could make having kids acceptable.

Then if it's truly a red line issue (one partner absolutely does not want to have kids, while the other does), both people will know that they at least tried very hard to work it out, and reached an understanding that there could be long-term unhappiness or resentment if the relationship persisted. Then there can be few to no regrets with moving on, which is difficult after being in a relationship for a long period of time.