OK, pretty difficult one and not sure if I am BU about it.
I have 2 DSDs. Lovely girls. GOod relationships with them etc., But both much older than my DC.
DSD1 has had 1 pretty serious BF, my DC got close to him and now don't get why he's no longer about.
WHile DSD1 is a very sensible, well rounded young girl, there is going to be another 'serious' BF in the future. As there should be. And I'm not trying to tie them down to one serious relationship for ever and ever amen..
But, my kids will get attached and then not understand why the chap has disappeared.
Actually, now I've written that down, it's not AIBU at all. It's how do I explain that my DSDs are older, will have - from time to time - relationships which don't last but it's fine because they are young.
Gah... think I just answered my own question.
As you were.