My fiance and I have a home together. He has an 18 year old son who just started college and has recently been dating a 20 year old. The girlfriend is not motivated (college or career wise) and the son keeps bringing her over and going directly to his room with the door shut. I told my fiance that I was concerned about him getting this girl pregnant, but my fiance doesn't appear to be concerned at all. I don't even like the fact that he's only 18 and is bringing a girl to his bedroom (in my house). I do feel a sense of responsibility. I'm very uncomfortable with the whole situation and am now questioning whether/not its a good idea to get married. I've told the son I'm not comfortable with his gf sleeping over, which he says he wouldn't do. I've also told him about the importance of using protection, whatever good that will do for a careless 18 year old. I've asked my fiance to have a sex talk with him, which he hasn't either because his ex already did or because he's just uncomfortable with it. All I can see is a pregnancy waiting to happen. The girlfriend is so unmotivated that I actually think she's looking for a pathway to child support. My fiance thinks I'm overly concerned, but I'm shell shocked at how little concern he's showing. He told me "the only way my son will learn is through experience." I responded to that by showing him our state's guidelines for child support. I use to think that my fiance was a good father, but now I see things differently, which is disppointing. I actually think he's played the role of being a buddy to his son, while leaving all the displinary, parenting things for his ex wife to shoulder. At this point, I don't know what to do or what to say so any advice/suggestions you can offer will be appreciated.