I can't say I'm sad but I'm not glad either. MJ could have a very strong impact in Peter and Gwen's relationship. I mean, perhaps Peter spends some time with MJ and this causes Peter to doubt his relationship with Gwen. This might leads to a temporary breakup, and just as Peter and Gwen are about to patch things up, she dies. Eventually, he finds comfort in the arms of MJ, but he never fully gets over Gwen's death. As usual, Gwen's death inspires him to continue fighting crime.