Men tell lies, string women along, and make false promises in romantic partnerships for the same reasons people do so in all relationships—they're selfish, cowardly, and want what they want. I had a boss who did that to me at work. There was a problem that needed to get resolved, and she was responsible for it. She kept promising me day after day that she would deal with it. The days turned into months, and she did nothing. She wanted to avoid conflict, make her life easier, and take no responsibility. She was lazy, scared, and weak. I was foolish to keep believing her promises and not give her an ultimatum: either resolve this issue by next week, or I'm resigning. I had known her for many years and liked her, but this was the first time I saw her in a difficult situation, and her true colors got revealed.
Maya Angelou famously said, “When someone shows you who they are, believe them.” When we're in relationships, our partners are giving us clues to their characters all the time. We need to be with them for a long time—facing challenges, stresses, and hardships as well as having fun—so we understand how they'll react in various situations. Unfortunately, some women have sex with men too soon in their relationships and then feel emotionally bonded to them before knowing their true nature. Then, when they start to see they're not men of integrity, they're hesitant to leave because they've slept with them. Bad mistake!
If you're discerning about men you're dating and taking the time to really get to know them, you won't get bulldozed by fake promises. Stay strong, stay independent, and don't fall for the guys with the sweet lines. There are so many great men out there (I'm married to one of them), but you need to be patient and work on yourself first.