1) Complain 2) Express discontent 3) Feel fretful 4) Fret 5) Kick 6) Kvetch 7) Plain 8) Quetch 9) Sound off 10) To complain 11) To fail 12) To regret 13) To wane 1) Fret 
to feel or express discontent or dejection
• (v. i.) To continue pining; to feel inward discontent which preys on the spirits; to indulge in envy or complaint; to murmur. • (n.) Vexation; mortification. • (v. i.) To fail; to wane.
Re·pine' intransitive verb [ Prefix re- + pine to languish.] 1. To fail; to wane. [ Obsolete] ' Reppening courage yields no foot to foe.' Spenser. 2. To continue pining; to feel inward discontent which preys on the spirits; to indulge in envy or complaint;...Re·pine' noun Vexation; mortification. [ Obsolete] Shak. 
at be discontented with 
[v] - express discontent
[Intelligent words] express discontent