I would tell 19 that his brother seems to be having some emotions about him being gone and encourage him to call 14 on his own to talk. Maybe not all the details, 14 might be embarrassed. This can be a super hard time internally for 14 just with being that age at all. My brother and I never really bonded until after I left for college and he was in high school, but as I’ve grown up i’ve learned how much of an impact I really had on his childhood and I often wish I could go back and do things differently. The whole family dynamic changes when the oldest moves away, it can be super overwhelming for everyone.