Correct, no justification to breed is needed whatsoever. Its a biological drive similar to eating and drinking, albeit on longer timescales and across generations rather than individuals.

However, thought processes like the one you identified above are probably adaptive, as gene lines which spend time trying to find the "justifiable reasons" for breeding were likely eliminated.

Gene lines where "I can raise my kids with like-minded community of peers", "I feel ready for more in life", and "sharing children with my parents, and letting my kids bond with healthy gradparents" (restatements of your phrasings) win out and reliably produce healthy offspring. So those reasons become strong motivators (despite being un-necessary justifications), that may seem irrational at first glance.