As /u/Tree_not_a_forest put said: people are generally on their best behavior in the beginning of a relationship/dating period/courtship.

Assuming that the guys you date are around your age (even with a wider range of age), you may be meeting people who were struggling to get their life in order, and it looked like they were juggling life okay, or maybe they had it easy enough until that point, but then life happens.

Unfortunately that it takes about 6+ months both for Life to Happen and for emotional attachments to start deepening. That means at the time when you start feeling more emotionally involved and attached with a guy is also when he probably feels the same as feels ready to let his guard down and be more vulnerable around you.

When the cracks in these guys started to appear, how did you handle them? It seems like, from your generalizations, that these guys started to have trouble keeping their shit together. Okay, that's life, and that happens, but how they handle the struggle to keep shit together matters to you, of course.

But I'm also asking how did you handle it when they started to struggle with it? With that one example, you said he turned to you to pick up the pieces. Is that the case for the other guys? Do you find yourself the "fixer" of other people's problems often? Just a wild speculation since there's not a lot to go on.

Is there really nothing in hindsight that could have given you a hint that maybe these guys were only projecting a good facade while hiding some cracks in the walls?

Like that one example, he was showing you who he was before you started picking up the pieces at the end. He was showing you who he was with the constant need for reassurance several times a day and

but all those things could've been avoided, he just... didn't

Sometimes it takes 6 months or so for these things to reveal themselves. It's like moving into a new apartment. You can look and visit a lot, but there's nothing like living in it for all 4 seasons to know if it's a good apartment or not, and sometimes shit happens anyways that no one could have predicated (shitty new neighbors, big earthquake, etc).