Are the following sentences correct?
1) They were dating for the longest time but then they broke up, because she cheated on him.
2) I've gone grocery shopping this morning.
3) I had never thought about it vs I have never thought about it. (which one is correct and why)
4) When I introduced my dad to my friend, they just laughed, and said they had already met each other/they have already met each other. (the second option sounds correct to me, but I would use present perfect rather than past perfect)
If there is the possibility to use both, please write some examples. It would be really really helpful.