How cum live always turn from being alright to complete shit just by sumeone sayin 1 phrase ?

Hey guys sorry been so long just been busy but i just wanted to put sumit.
My life at the mo is alright i guess every1 seems happy. My sons happy and heaithy, familys alright. But i just feel so alone and lonely and dont no y but IM DETERMINED NOT TO SHOW IT coz no1 will understand :(
Anyway talk to u soon guy.
And remember KEEP SMILING :)