My fiancé's parents are older than both of mine. It's gonna be rough losing them as well. She's an only child and though they're divorced they became good friends through and for her.
I've started to try to build a relationship between her and my family more lately.
I can go weeks without talking to mine, random texts, "I'm alive" messages have always sufficed. But it's important to me that she starts to feel comfortable with building a relationship with them.

I lost my grandma randomly in 2008. She one of my closest friends. That really fucked me up. I don't think I expected her to be around forever. But more that she'd fade and you can mentally prepare for something like that.