Unfortunately there is never any guarantees in life. But one way I look at it, you can avoid the depth of feelings and have life that is ok but nothing exciting, (and brings its own bad feelings, maybe frustration, loneliness or restlessness) or you can practice being brave - practice feeling and connecting with emotions and experience amazing times. Along with the good times you will capture lovely memories, and those memories can help you through the bad times
The more you practice connecting with life, the more you'll build your confidence and resilience.
Just like sandcastles, they may not last forever and wash back in to the sea, but make our lives so much more interesting and bring joy to us and those around us
If I think about my relationships (partner, family, friends), i know I will be utterly devastated again when I lose someone again, but I am so grateful for the amazing memories and experiences I have gathered so far - I try to make the most of each day, that helps me
Hope this makes some sense!