the only relationship advice my grandfather has ever given me, was what to say to my husband whenever we leave. he told me to always say "i love you be careful" before he leaves for work, or whenever we get off the phone, because the world is so complicated you never know what your last words to them will be. he told me to never leave before we've compromised in a fight, to never just let an arguement afloat, because you never know when someone will be gone forever.
he talked about how he wonders how many people that died in hurricane katrina, or on september 11th, were on bad times with their spouse before they died. so for his entire 60 years of marriage to my grandma, every time they have left each other they both say, "i love you be careful." i think its one of the wisest things anyone has ever told me.