Your a soccer manager.
Frustration will hardly set in, in Football Manager because in the end of the day its only a computer game. But loosing a game can be upsetting if you really need or expected to win. To find a winning tactic you will often have to keep a steady team for a long period of time.
I played as Ukranian side Arsenal Kiev for two seasons and could hardly purchase any new players. Although I learnt some interesting tactics! You could find it a bit dull just to have to be so patient in order for your team to make a break and do well. Its a bit of luck over managing skill sometimes and this is probably the most frustrating thing about your team loosing, or a player wanting to leave.