There are several signs that might have been overlooked. For instance, if your friend was constantly talking about death or suicide in a non - joking way. Changes in sleeping or eating patterns, like not sleeping at all or overeating, could be signs too. Also, a loss of interest in activities they used to love is a red flag. Maybe they stopped going to their favorite hobby club or quit playing a sport they were passionate about.
Warning signs can be quite subtle sometimes. One possible sign could be an increase in alcohol or drug use. If your friend was self - harming, like cutting or burning themselves, that's a very serious warning. Social isolation is another factor. If they started avoiding friends and family without a good reason, it might have been a sign. It's important to note that not all people who show these signs will attempt suicide, but they are things to be aware of.