Ex has them for 3 days but when he isn't with them he'll text things like "I'm missing you" "love you so much,can't wait until you're back home" I've seen the messages appear on their phones/iPods (DD is only 8 so I do check her iPod) but I don't snoop!
I'm sure he misses them just as I do when they aren't with me but it's like he needs constant reassurance from them. My DD rarely bothers to answer & she sometimes rolls her eyes at the texts. I can imagine that my 2 boys tell him what he wants to hear.
It's like he has to be reminding them constantly that he's there. They love their dad and have a good relationship with him I'm not sure why he so needy!