The TBMs are trying to convince themselves, bless their hearts.
Smugly assuming that the Mormon gospel makes them happier than other people is one of the last straws they have to hold on to. Advertising their "one true happiness" helps boost their fragile egos now that the Mormon church becomes a bigger joke daily.
Really happy people are happy because they are living their lives to the fullest an not wasting time bragging about how happy they are. I am surrounded by 100% non-mormons most of the time and nobody ever talks about how happy they are. Just isn't a topic that comes up.
My TBM mother on the other hand is like your family, just without the FaceBook. I don't mind them mentioning they are happy, but why do Mormons make it seem like it is a contest?
I remember my mother telling me not to write anything negative in my journal because we want our progeny to know we were happy because we're Mormon. She said if negative things happened I should wait until it all worked out for the better, then I could write about it with the happy ending.
She explained this by pointing out that the pioneer women must have had some pretty bad days and were probably very discouraged at times but they managed to write positive things because they had The Church (TM). Women in the church now can go back and read the pioneer journals and be uplifted by their positivity and that's the legacy we want to leave to our descendants too.
I kept a journal for a while after we were married. My wife would read what I had written and would make comments so I started writing what she wanted to read. Like the church, it wasn't true, but we got along better when she felt reassured. And, I too like happy endings.
You also have to remember that being a young adult can be a time of turmoil. The 20s and even into your 30s can be difficult because you are trying to get some of your biggest life decisions figured out -- career, mate, children, life balance, finances, etc. I think we get this false image from TV that being a young adult is a carefree time, but I think the image is a false one. That period of your life can have more than its fair share of challenges.
I got happier as I got older. By the time I hit my 50s, I was really happy. It's possible that your parents have hit that time of their lives as well.
I mentioned this in another post that a couple years ago when it came out that Utah had one of the US' highest rates for anti-depressants, the church spokesman basically said that members don't try and fight depression with drugs or alcohol, they go to their doctor and get legal prescriptions, but...
...they're members of the COTCOJCOLDS, they have the One True and Restored Gospel...they *should* be happy beyond happy!!
Oh, wait, are they happy, or are they supposed to endure (which doesn't sound too happy) until the end? In mormonism, I guess they cover all bases)
I was happy while as a member of the LDS Church. No delusion. Nobody is happy all the time, but we all strive to find happiness in our lives. Life is not easy for anyone. We all have to spend a lot of time just working hard, and keeping things together, and as a Mormon I did the same, like most folks. Sure Mormonism was my World View at the time. It was working for me, at that time. And, of course, there were struggles. Just like now when I am not a member of the LDS Church. The notion of the Mormon's "Gospel" is very comforting to them. I have friends that voice that sentiment. That's their World View. They accept it as valid for them. And, that is OK. We all get to do that.
Since creating my own World View I can say I have found a lot more contentment and inner peace and happiness when I let go of any need from religion to govern my life. Those intrusions are not necessary and not productive.
So, I was happy then, I am happy now. I have taken my power back and own it and created what works for me now which is not the same thing that worked in the past.
So, I refrain from judging anyone else's happiness.