I'll try to keep it brief.

I have a SS14, I met the DW about 7 years ago. I have known SS14 since he was 7. His bio-father had very little relationship with him then, but it has deteriorated to the point hat they have no relationship at all anymore, and haven't for several years now.

I never tried to be a replacement father, but I did try to be a good stepdad. We hung out, played video games, and did spend time together. I allowed the DW to discipline and rarely ever even raised my voice to them (I have a SD17 also). I would say we had a pretty good relationship when he was younger. I basically just always tried to be there for them, financially and emotionally. If they thought of me as "dad" then I was fine with that,but I never tried to force that either.

Over the years, they began to change and became very different people. We had very few interests anymore. I posted about it on the teenage stepchildren board ("I don't like my stepkids very much"). Even though SS14 was unpleasant much of the time, I didn't disengage. I still tried to hang in there and maintain a relationship of some kind, even though it did become more distant.

Last night there was s huge blowup. SS14 has been totally out of control for way over a year (pot smoking, lying, stealing, etc), and very disrespectful to me lately. I got in his face and he had a screaming fit. After things calmed a bit, he said he wanted to talk to his mother only. I could hear the entire conversation. He said that he never thought of me as a dad and that we never had a good relationship, and that he does not think I was ever a good stepfather to him. He said he does not consider me as part of the family, and that he basically did not want to have anything to do with me anymore. I was shocked to hear these things. I'm certainly not perfect, but I did think I put forth the effort over the years to not have him crap on me like that.

The people that have said you really have very little impact when trying to get involved as a stepparent were right. If the stepkids want to have a relationship with you then I would say give them that. But if they reject it, don't question yourself at all. Disengage and leave it at that.