tips/advice for a strong relationship?

my bf & i have been together for over a year now & hes a senior going to college next year (im a junior). and we plan on moving in together once i graduate and going to the same college. everything sounds so planned out and perfect but i know its not going to go as planned and that life can switch up on you. all i ask is that we stay together because he’s a great guy and my first love. i hope to last forever but even if we dont, i’d love advice for how to keep this relationship strong for as long as possible!! thank you ❤️