My best friend is acting crazy?

ive been best friends with this guy for 3 years now, and he met this chick online 2 years ago and ever since then hes changed alot. they only see eachother once every 2 months because of the distance and when i tell him itll never work out he gets mad. and apaprently he "loves" her and she "loves" him too, but shes 14 and hes 16. thats impossible theyre too young and they always say how in 10 years or whatever theyll get married and have kids which is total bull bcs come on theyre still way too young to even know what theyre talking about not to mention to know what love is. he always talks to her every spare second he has and now when i hang out with him if she texts him he suddenly stops talking to me and starts basically drooling over the text message and forgets that im there. and its annoying how he always talks about her and when we hang out and do stuff hes just different like he doesnt want to be there. help?