One who is constantly subdued by his partner/wife/fiance to the point where he has no identity of his own, rather just a puppet that she speaks through.
man who cant get a hard on, therefore is a useless cunt, useless cunt therefore being a softcock, softcock can descibe someone who cant or wont do something whatever that might be
Susana said she'd go out on the weekend. When she realized she wouldn't be able to keep up, she decided to make other plans. Therefore, Susana is a softcock.