army girlfriend

so i've been dating my boyfriend for quite awhile, i've dealt with him leaving for a few weeks at a time, weekends etc. but he's going to be leaving again for almost 3 months in a few months..which will be the longest i've been away from him yet. our relationship is reasonably strong for the most part, trustworthy and very open. but i'm full of mixed feelings on him leaving for a big gap of time. i think what stresses me out the most is we spend every day together besides working and our school schedules. so with him leaving i'm worried about keeping things exciting and positive while he's away, considering its going to be just as hard on him. any advice on this ? or even advice on military relationships in general? i've had boyfriends in the past but this life style is strange at adjusting to..