We have an agreement, that when we're on a date, only IMPORTANT interruptions (issues with kids or emergency) are allowed.
I have a personal rule, that bf and husband accept, that I do not text/call if I'm on a date.
THAT SAID-if I'm "out of town" that's not a date, that's a vacation, even if it's a couple trip.
So, if our time together will mean more than a few hours away, we have an understanding of "text/call" time for our other partner before bed and other specified times of the day that are non-disruptive to our romantic time.
My contact IS less when I'm out like that, but it's not GONE.
I'd say that it's VERY important to differentiate between your feeling jealous of HER-versus your hurt over not continuing to be treated as meaningful to HIM.
I.E. if you need him to text you once or twice a day when he's out of town-that's not about her. That woudl be true even if he were on a business trip.
you want him to text you BECAUSE he's with her and you are jealous.
One is an issue you need to work on in yourself. The other is simply a matter of identifying your needs and laying them out so that they can be met.