I kind of think that the older you get, subconsciously you realise you have less time ahead, and are less able to cope with other peoples nonsense.
If they let you down, it is much more of an effort to forgive and go back to them. Easier to walk away.
This will result in you having no friends though, so if that is okay with you – go ahead. But if it concerns you, maybe give that Friend a little break, try to forgive them for being human, and then give them another go. Maybe three strikes and then walk away as a compromise?