Add this as a fundamental part of your frame and it will save you lots of time and problems. Think of it as a firewall rule for outgoing traffic.
Let's step back. Out of all the things one might talk about, why choose something negative? Just on general principle, I don't want to spend any time on negative shit. I want to spend my time on positive shit. Sentiments shared by most of mankind, surely.
But let's say I am. I'm voluntarily talking about negative shit. I must have a really, really, really good reason. Because lest I forget, I am forcing my audience to feel bad. To deal with negative shit. Essentially, I am making them suffer the same emotional consequences that I have incurred. So this reason needs to explain how their awareness is of such benefit that it's worth the pain that it brings along.
So what are the rational reasons for sharing something negative about me or my life? There is only one: they can offer a solution, if one even exists. That's it. Unless your problem has a solution, and unless you think your audience has it, then never talk about negative shit, period. If you must, then use a pro or a priest. Both trades exist almost solely to listen to people talk about their problems. It's enough that you have to feel bad about shit. Don't make it worse by forcing the people you care about to feel bad, too.
When can one share about their negative shit? After you win. Because then it becomes a positive story about success. You could almost say that talking about a negative situation as it's happening is premature, since you don't know how it's going to turn out. You might well be documenting for your listeners a grand fail, in real time.
Notice this is before we even get to girls, or not showing weakness, or the myriad other considerations RPers need to navigate. To have rational, well-considered first principles behind every interaction is key to building a frame you don't have to think about all the time.
P.S. I think the reason why some people get a 'be happy' vibe from this is my use of 'positive,' particularly when used opposite 'negative.'
In this context I'm using it as a stand-in for 'anything that has merit' - NOT in the 'don't worry be happy' matrice.
This choice is a simple binary and should happen instinctively, frankly. Pain, or not.