Some relationships just end. My ex and I just fell out of love with each other. It's not that either of us were bad people or that one person totally ruined it. The whole point of growing up and growing older is learning and growing both emotionally and mentally. Hopefully you grow together but sometimes you grow apart. That doesn't mean that its totally one person's fault or another's. I ended up a totally different person after 3 years of my last relationship and so was he. But the problem was, we grew in opposite directions. He became more uptight and nervous and anxious and I became more liberal, open, free-spirited. Don't try to blame either of you, it will only cause resentment. Just admit that neither of you are as 'into it' as you used to be and maybe its time to go your separate ways.