Yeah I think that the ring made a huge difference to Elena's feelings in the end definitely, but Damon didn't know that Jeremy was wearing the ring at the time, so IMO she should have given a lot more thought to the risk to her loved ones if Damon did decide to lash out again. Indeed Damon almost kills Jeremy a second time in season 5 when he handles their break-up badly, again because of Katherine riling him up

And putting Elena first is one thing, but it gets into super fucked-up territory when they are preparing to sacrifice others to keep Elena safe, yet the show rarely questions that Elena kept hanging out with them, in spite of the fact that they had a coin toss for example over which of them would kill Bonnie's Mother