The most common way of saying this in French is Ça me manque de… and then of course whatever you miss doing.
C'est elle qui m'a dit ça.
Expressing i miss you with je ne suis pas bien sans toi This one is perfect for those looking for a very heartfelt way to express that they miss someone.
Let's say the woman left the day before as she accepted a job offer in a different city.
Man : I miss you already.
Si vous-autres a fini de manger, on va sortir dessus la galerie pour prendre du café.