Why do people stay years with people they never end up marrying?

I've met few older dudes in their late 30s to early 40s. Both have been in multiple long term relationships for 7-10 years. One guy lived with his ex for 8 years. Another guy dated an older woman for 10 years throughout his 20s then wasted time dating another girl for 7 years, now he is in his early 40s and desperate to start a family. Both are very desperate. My question is... how do you spend so many years living with someone but yet never end up starting a family with them. Why waste years of your life in a relationship that goes no where? Now they're getting old, aging out of the dating market, all their peers married

It doesn't take 7 to 10 years to know If you have found the right person.

Why do people stay years with people they never end up marrying?
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