If you want a plant to grow, you have to water it. You have to tend to it, nourish the soil, give it the right amount of sunlight, protect it from the harsh winds, and give it love and energy every single day. Otherwise it will die. This principle applies to your relationships too. The more love, time and energy you invest in them, and the more consistent your efforts, the more your relationships will grow, open wider and go deeper.
Phil and I are coming up to almost eight years of relationship and