I'm sure Troi was involved, one deadly glare from her & other women are quite likely to get the impression that she's got firmly established designs on our boy Will. Wesley's constant interruptions & the times he's walked in on Jean Luc with Bev, and J.L. asking him to step in during Captain Picard Day festivities ...I'm sure were more than enough to make Will reconsider how important a child would be to him. And Will's difficult relationship with his dad being an absentee parent...again, made him waffle slightly. In addition to the stunned look on his face during the close-call with the grey alien screwing with his mind and holodeck dates with Minuette.