My daughter is dating a much older man
I don't know if it helps, but when I met my girlfriend she was 16 and I was 23, one year later we came together.At that age I was working but lived with my mother.She was grown up enough in thinking and I never felt like I'm dating a "child".I was able to share my feelings and my experience about finishing exams at high school, about university also I was able to live those things again.She went to high school and lived with her parents.Since then almost 4 years past and we live together in another city and we are both happy and in love.
My relationship with my wife lasted 16 years and produced 3 lovely children. However, as MY children reach their teenage years I of course see everything from the perspective as a parent.
A theoretical 17 year old man could equally, if not more so, be with her for only one reason.
Equally, becoming pregnant and having to postpone things such as career isn't age relevant. If the relationship develops, you could express your concerns, though not in a judgemental way - otherwise you could risk damaging your relationship with your daughter and pushing them together.
Recognize the powerful grip the 25 yr old has and that is normal. I would try and create a containment bubble around a situation you have limited control over but in reality you do have a way to contain the situation. Reinforce her education about the risks of getting pregnant and maybe set some soft rules like 'education comes first' Maybe she is in sixth form. It could be that the relationship is successful but if something goes wrong be sure she knows you are there for her if things collapse.
I get myself sick with worry in regards to my kids.