When situations are uncertain it is usually best not to make lifetime decisions. That was Paul's advice to young men facing the possibility of significant persecution. It would be a difficult time to marry when the believers might have to relocate at short notice. However the Apostle realised that some betrothed couples were deeply in love and wanted to marry, even if it meant facing persecution together, whatever that might mean for their extended families. For those people, they should marry rather than find that they are unable to control their passions, leading to immorality.