Well I guess it a great problem if it would happen to me. You know, if you are a gal and your boyfriend is 10+ years older than you, that's ok. But while the situation reverses, it will be a little bit intractable.
My suggestion is, look before you leap. Think about if two of you married, after your passion passed, your daughter(as you just said) may bring a lot of responsibilities to you. And you may tired before you could afford. Maybe I'm a little meddlesome but, this is my suggestion. :)