Wouldn't it be nice if we could know these things for sure, about the future?
It depends on your daughter's age, her personality, how secure she feels with you... and the personality of the guy!
If things seem terribly prickly and unpleasant between your daughter and a new guy at first, you should certainly proceed cautiously and take time to determine whether she just resents his presence in your life, or whether the two of them just don't mesh. On the one hand, you don't want to dump a great guy just because things don't go smashingly in the beginning with your daughter. Maybe she's the type who will instinctively need to test a new guy, to see if he'll stick around and stay interested, even when she's not on her best behavior. On the other hand, you sure don't want her to think you'll choose a guy over her. Even if someone you date is a good person, he could still be a bad match for her. Only time and a lot of objective honesty on your part can distinguish between these two possibilities.
However, you should also proceed cautiously if a new guy seems too eager and too perfect with your daughter. It's right for a man who's very interested in you to want to impress you by being nice to your kid. It's also great if he and your kid just naturally get along well. But a genuine close relationship between a child and a would-be step-parent should take some time to grow. A guy who seems amazingly eager to entertain your kid, be her best friend - and spend time alone with her - could be a problem. Things that seem too good to be true sometimes are. I'm sure that no mom who married/dated/moved in with a child molester ever imagined he could be one!
There are 2 schools of thought about introducing your kid to dates:
* Why would you want to get attached to someone who's not going to work out with your kid? So introduce them from the beginning. She's the most important part of your life, after all.
* Your kid shouldn't have to accompany you on the emotional roller-coaster of dating. So don't introduce her until you've spent enough time with a guy to know "he's the one" - as long as he gets along with your kid.
I highly favor the 2nd approach. It focuses more on what's appropriate for the kid than what's helpful to the parent. Your daughter could get attached to a really personable guy that you wind up not wanting to stay with. Kids should not have to process all the emotional distractions of a parent's dating life. Weed out the people who won't make the cut, before she gets involved.
As for me - I can't say it was what I expected, because when I met my husband I wasn't looking for a relationship. I hadn't defined what I expected. But, in retrospect, I think things developed perfectly. He was nice to my kids and made some special efforts to do nice things for them and they liked him. But there was never any question that I was his main focus. He never behaved in a way that made it seem like he was super-excited about getting close to them, except for the fact that he wanted to be close to me, and they were important to me. Also, he never, ever asked or hoped for me to do anything with him that would've been inappropriate for my kids. He didn't want them to spend more time with their Dad so he and I could have more time alone. He didn't want me to stick them in front of the TV or put them to bed early, so I could focus on him. He didn't want to spend the night at my house (at least, not while they were home) or to move in and play step-dad before he was Step-Dad. He was really great about being polite and friendly to their Dad even when I was irritated with him (my ex). My husband consciously treated and talked about my ex the way he would want his kids' step-dad to treat and talk about him. All of those things were very important and made me feel comfortable, as our relationship progressed.
Come to think of it, here's another thing that was important to me - and it's probably unusual: My husband and I spent time around each other and got to know each other pretty well for a long time (~a year) before we ever talked about dating or acted romantic with each other. Then, when we finally discussed our attraction to each other, he came right out and told me that - based on what he already knew about me - his long-term desire was marriage. He wasn't proposing before our first date. He was just acknowledging that, with kids in tow, he knew I didn't want to get attached and invest a lot of time in something that was "just for fun" or up in the air. He wanted me to know up front that as long as things progressed the way he expected them to, based on the rapport we already had, he would want to marry me and be a stepparent to my kids. He wanted me to feel assured that I wouldn't date him for years on end, only to have him eventually declare, "Well, I do love you. But I'm not sure I want to get married again," or "I'm not sure I want the commitment of your kids." It was old-fashioned... but it's a great start to a dating relationship, if you can swing it!!