Most of the things that should have been red flags that the relationship wouldn't work out, I really only saw how wrong they were in hindsight.
We were spending a weekend together, but she bailed on it to go home at 3am Saturday morning (we lived an hour and a half apart to boot) because my dog crying to go potty kept waking her up. But when I went to her place she wanted me to stay in her living room and just hang out watching TV while she slept all day. If I went home instead of sitting in her living room absorbing daytime TV she'd pout and say I was making her "feel shitty".
Near the end of the relationship she kept bailing on date nights to catch up on her sleep, or pout and ask me if I could drive over to her instead of her coming to see me because she was just sooo tired. The final three months of the relationship I did 100% of the driving (3 hours total, round trip) and she kept having reasons she couldn't do any of the driving to come see me instead. My friends and family thought we had broken up two months before we actually DID break up, because they just never ever saw her and me together.
The number one thing that should have sent me running, though, was the time she told me to my face that "for her own well-being" if she ever felt she cared more for me than for herself, she'd dump me on the spot. I should have just packed it in right then and there.
When I look back on it, the best lesson I learned from her was to just be upfront with people about how I feel. I spent so much time choking back how frustrated it made me to have to do all the driving or not saying anything when everything I said and did made her "feel shitty" because I didn't want to piss her off so much she dumped me. But that happened anyway regardless of how understanding and accommodating I tried to be. Lots of date nights were me driving 1.5 hours there and 1.5 hours back just to lay in bed next to her snuggling while she worked up the will to get out of her fucking bed and DO something with the evening. And I let it happen, I said nothing about how aggravating it was to be second fiddle to her damn bed because I wanted to try and make things work. And I got dumped anyway because me letting her call all the damn shots in the relationship made her "feel shitty".
The best lesson she taught me was to just not give a shit if the relationship works out. It will or it won't, but there's nothing to be gained from throwing yourself out there for someone elses' benefit. They won't return the favor.