
“Just give it time”

It’s actually very sound and correct advice, that’s why it’s so infuriating. Obviously with time, whether it’s a tricky decision, a bad breakup, or a loss, you will feel better. But we’re immediate creatures, who see little value in the age-old wisdom of ‘just wait and see’ because we can’t wait 30 minutes for a takeout without starting to regress to our lizard brains.
“Try to test them”

As a general rule, unless you’re 99% sure they are cheating on you, you shouldn’t be playing covert spy-ops with people. Having suspicions is quite natural, and your partner should be reassuring and hear you out at least. If you reach the point you feel you need to resort to some kind of test, that’s a clear sign to leave the relationship.
“I always knew there was something off”

Thank you, captain hindsight. Any chance of next week’s lottery numbers while you’re perched so high above the mere mortals who operate without ESP? People who say things like this, especially as an initial response to you asking for advice, are immediately making it about themselves, not offering sympathy or anything useful.
“Chose the other woman, not the one who made you question her”

This quote is often attributed to Johnny Depp, a noted expert on healthy relationships. It only takes a couple of seconds of analysis from a developed mind to realize all this does is excuse men who believe in evolutionary psychology, who think men are wanderers and conquerors. You have to put in effort to make a relationship work, not give up.
“Try a dramatic gesture”

Now, this isn’t awful advice, sometimes something a little extra is exactly what the situation needs. But there’s a huge range of behaviors that count as ‘dramatic’ and many of them veer into ‘wildly misjudged the situation’ territory pretty quickly. Think of a proposal as an apology for a spat, that’s the kind of proportionality you want to avoid.
“Just let it go”

Sometimes this is a great piece of advice to give to yourself. After a decent reflection, you’ll know in the grand scheme of things if your problem is minor or major. Coming from someone else, it’s putting the cart before the horse a little bit. If it were that simple, they would have, that’s why they came to you. Cut it out, Elsa.
“If it’s meant to be, it will be”

This isn’t advice at all, it encourages complete passivity, which you could easily have come up with on your own by just falling asleep. It’s similar to the ‘wait and see’ approach but with an added element of cosmic mysticism. It’s fine to believe all that, but for those that don’t, it’s similar to just giving up hope.
‘Your standards are too high’

This very impolitely suggests a lack of agency on your part, and also implies that whatever issue you felt worth bringing to them isn’t an issue at all. It could be described as victim blaming in a sense, it’s blaming your problem on you, that it’s the standard you somehow deserve.
“They get angry because they care so much”

Justifying angry or even violent behavior as a show of passion is deeply dangerous, and only keeps people in harms way. It could be passion, it could also be an unhealthy codependency, but both are equally poor reasons to excuse frequent anger. Some people have trouble regulating emotions, and there are ways to fix that if you’re willing to work toward it.
“But you’ve already been together for so long”

While a long-lasting relationship is a sign that you and your partner are good at problem-solving together, it doesn’t necessarily mean you’re both happy or even content. The length of time doesn’t matter as much as the quality, if neither of you is feeling fulfilled then what good is the track record? To cry over as you question what you have become.