SUBREDDIT: r/relationships
TITLE: Sometimes I [21M] eat dinners with friend [22F] who my GF [20F] knows I once liked. Don't want GF to be jealous. Advice?
POST: My girlfriend [20F] and I have been together for a while now. Most of it has been long distance. Due to just casual conversation before we were ever dating, my girlfriend knows that I liked another girl at Uni for some time a while ago. The thing is, this girl and I are still pretty good friends (although I have no remaining degree of attraction to her) and grab dinner in the dining hall a fair bit to catch up, as I do with all my friends. Truly nothing out of the norm. That's the extent of it. Nothing romantic ever came close to happening with this friend in the past.

I'm a bit concerned about my girlfriend being worried when she comes home though. On one hand, I don't want to throw away a (very casual) friendship with someone, but I also don't want my girlfriend to feel jealous if I'm having dinner with this friend she knows I once liked (and who my girlfriend doesn't particularly like very much). Is there any way for me to mitigate this? 

Someone on here might ask why I'm concerned if there's truly nothing to be worried about with this friend or question if my girlfriend is insecure. Both are not true. Rather, if I were in her situation I could imagine feeling a bit uncomfortable and wouldn't want her to have to feel that way. But maybe that's my own problem...
TL;DR: 
Girlfriend [20F] knows I liked another girl at Uni before her. Nothing ever came close to coming from it. Still friends with girl. Want to not cause any tension. Advice?