Separation Anxiety

My 8 month old all of a sudden has separation anxiety at night. It just so happens to coincide with my husband going out of town and my LOs new found ability to pull himself up. When he wakes up in the middle of the night he stands up in his crib and bawls until I go into his room and soothe him. Then he’s completely fine. I tried sitting across the room until he falls asleep but he seems to need my touch. I can get him calmed down, but as soon as I leave the room, he is back at it. Anyone else experiencing this? Has anyone figured out a solution?