The first one wasn't his. For all we know, she denouced the first one's father for having abandoned her when she started sleeping with this dude, and maybe he promised not to be that kind of guy to her. Then look what happened to him—she killed his child.
There's a reason the old-timers looked down on sex outside of marriage. It rarely works out well for either male or female. People talk a lot about today's entitled women, but the male entitlement to sex without either commitment or love is the other driver in society's car crash.
lol I *am* the old timers. :-)