Jalter has joined the conversationMarie Antoinette: you know nothing about betrayal
Gudao: laughs in insanity
Lewd Nun: well this is gonna add 6 more months to his therapy
Let her eat soap!Well, that's quite the loose tongue. Gonna need some adjustments for that
After doing few events... I think I kinda get it DXTo be fair, 'betrayal' is just kind of par for the course as far as Servants work- they're working with you now, but they might get summoned by someone else and you'll have to fight against them later. This is part of the reason why they're not supposed to remember their previous summonings, it's not supposed to be personal (that, and they're not supposed to get re-summoned often enough for that to be an issue). They remember the Chaldea summonings because the Chaldea system is different than the one used in the anime/games.
It's also worth noting that as far as normal Grail Wars go, the odds of summoning the same Servant more than once are actually quite low; unless you have something extremely specific to one of them (and it's the real deal, not a fake relic) in order to call one specific Servant (like one of Solomon's ten rings, or Shirou havingAfter doing few events... I think I kinda get it DX