I heard a guy say one time that he calls his wife a couple times a day for no reason at all. He just wants her to know that he's thinking of her.
I took this guy up on his advice and I probably call my wife at least once a day for no reason at all. No appointment to schedule. No mutual chore that we need to embark upon. No item on the agenda. None of that. I just call to say "Hi, how are you?" That's it.
This is very vulnerable for us as men and maybe even downright scary, but give it a try. The reason you're calling isn't for an item on the agenda. It's just so she knows you're thinking of her and her heart. It helps her to feel more open and safe with you.
Oh, and it doesn't have to be a 30 minute phone call that's going to ruin work for you. My calls are usually an average of 3 minutes, which surprises me because we like to talk to each other. Anyway, if your wife is a talker, just tell her you need to get back to work but you wanted to know how she was doing. That's okay.
Of course, it can get more complicated than that and who's to say who's working during what hours and when each of you is free or not free for a phone call. Maybe she's a nurse and busier than you and you have to leave a voicemail. The point is that she knows your desire is there. She'll appreciate the voicemail as well.
Good luck men.