There's an old saying which goes "no man is an island", and it's very true. Nobody chooses a life of loneliness, and a loving relationship which goes beyond the basics of sexual attraction is built on a desire to share our lives with another person. One of the most important things you can offer is companionship.
For a man to stay with you forever, you must become his trusted and most favorite companion; both his lover and his best friend, and his partner in crime! Keep his secrets, share his joys and pains, celebrate the good times and commiserate the worst. Walk beside him on his journey through life, side by side, every step of the way, and you'll become the person he can't replace - and the one thing he couldn't face life without.