Pretty sure Trunks was just depressed that his only hope got their asses kicked plus he found out his enemy is literally immortal.
And bout Gohan, I do agree that it's just one big disappointment with that guy. He used to be stronger than SSJ3 Goku! Yes, he doesn't like fighting and yes both Vegeta and Goku are stronger than him again so he doesn't think they need him. Let's hope they find some use for him after or during this arc.