My relationship with my girlfriend (of 10 years) is a tremendous source of happiness for me. Not only do I feel a near-limitless feeling of love for her, but expressing that love makes me so much more "loving" and open to others as well. But I'm not sure I would have made it to this point so easily, had it not been for those two simple pieces of advice.
I had a tendency to be critical of people who I was closest with (read: my girlfriend) since my mother had been the same way with my father, and I assumed that was natural. Even when I understood that negative comments should be sparing, and that I should be as free as possible with positive comments, making the change was difficult. But it was the other piece of advice that made it possible.
When I began to view the relationship not as something static, but more like a skill that you build over time, my attitude towards the potential for change shifted. I wanted to be "really good at my relationship" with her. And I knew that the only way to do that was to approach it like any other activity -- focus on a goal, and practice. At first it was difficult, but I focused on reducing the negative comments, and trying to compliment her more. Progress was slow, but with the right mindset, I began to change.
Since then, we've both changed ourselves in many different ways for each other. Because we were both committed, and had the right attitude towards our relationship, we've developed an incredible level of trust that lets us express a very deep feeling of love for each other. We often joke that we've never loved each other more than we do right now. The amazing thing is that it's true -- because we keep working at it, our love continues to grow.
Being willing to change for your partner is not a risky move -- it's the only way to find true happiness in a relationship.