Ridiculous behavior

Why do girls forget their own ambitions as soon as they get into a relationship? Only to put all of their time and energy into their boyfriend's/husband's ambitions. Being together doesn't mean focusing on ONE person's goals. I'm so sick of seeing girls my age completely lose their identity in their boyfriend and be perfectly fine with giving up everything they've ever wanted. I was talking to my mom the other night about the cruise ship idea and she said, "You better do it now while you're single, because once you're in a relationship it'll be different. You may not want to." WHAT?! Just because I find someone to be with doesn't mean I'm going to decide to do whatever he tells me and forget my own thoughts. If he's the right person he'll support what I want to do, the same way I would support him. Girls are so afraid of telling a guy what they think for fear of upsetting him, but if he tells them what they think it's the gospel truth. It gets old to sit and watch people you care about in this situation.