There is also availability from GVA on the 20th at the low level. GVA isn't much worse than BRU when it comes to train travel time. I don't think leaving a day earlier would be in issue in this case because the travel is overnight on a non-stop flight. Probably the best option here.

You can travel on your dates via ZRH. ZRH is 4.5 hours away, or most likely a 100E plane flight.

I'm not on KVS so I can't do much better right now. This isn't a difficult situation if you are willing to use nearby airports and be slightly flexible with your dates.

P.S. - French girls are tough. I've dated 2.