I think the possiblity of lossing someone you love became more real to her after that, but I also have to think that it's because he was her one, big, true love that she also didn't care to do much dating; she loved Andy something fierce and you just don't forget someone like that, heck, look at everyone she dated after him - they all favored him in a way, be it looks or whatever. The one guy who could ever tame her and get her to really settle down that she'd love for all time was him I think, no one could measure up to her standards accept Andy because all she ever wanted was him to start with. These two were true soulmates and once he died....it was pretty much the end for Prue as they showed, she was just too devoted to him and the possiblity of what happened repeating itself was enough for her never to have a successful relationship I think. Sure Bane might have worked, but she would never love him like she did Andy...but that could just be me.