why do I get dumped for traits I didn't have when we met?

I've been dumped 3 times for the following reasons: <br><br>1. I was a "dog" (I guess I was too much of a bad boy/idk) - I didn't know how to be a bad boy when we met, I learned by watching her ex who she was still in love with and by asking her for advice. I even tried to do things that would make her uncomfortable to see how much she likes/didn't like it. She admitted she cheated on me with someone else and broke up with me for being a dog. She is now engaged and pregnant with this man. I tried to fight for the relationship but she chose to leave.<br><br>2. I was boring - I met this woman through a friend and she knew I was an engineer. I think she was expecting a stereotypical nerd that would always listen and do what she says. I was very busy with work and didn't have time for much. She wanted to go out and have fun every weekend but that made me tired and feel/look worn out for work so I declined most of the time. She broke up with me and said I was boring. I tried to fight for the relationship but she chose to leave.<br><br>3. I was too nice - I met this woman at a grocery store and we instantly hit it off. She had a tough time as a single mom and I wanted to help. I gave her money for food/gas/etc, helped her move, and helped her son with his school work. I was always there for her. She later told me she didn't know how to act around someone that is so nice to her. She said she only knows how to act around people who treat her like shit. She broke up with me because I was too nice. I tried to fight for the relationship but she chose to leave.<br><br>Maybe I'm just too dumb to get it, but what the fuck is wrong with women? Why do they change what they want? Do they just want a change of pace? I've read some articles and it sounds like a lot of women do this. I really dislike that I can't rely on a woman to stick around.