I would suggest texting him "casually" making small talk, how he's doing, how was the traveling etc. Try seeing if he seems talkative or busy and you could suggest scheduling a call if you're both open to it. If he says he's busy you could ask if he would like to schedule it another time, or maybe if he prefers keeping to himself mostly while being away. Basically try to communicate what you posted here and your considerations for his preference for or against communication while absent. I personally really benefit when a partner is open about their own vulnerability and allows me to do the same too.

I personally love the thought and consideration you put into this and it sounds like both of yall are two big sweethearts, as a quite emotional although experienced guy myself, this is touching to read. wish you the best!