I don't know what exact you mean 民國97年 (2008) or 1997.
But anyway, here is the situation:
1. If it is 1997, he has passed his chance for 6 years.
2. If it is 2008, he still has to wait for another 5 years.
Since he is sponsored by his mother who is a Legal Permanent Resident, he will be under Visa Category F2B (Family Preference Priority 2B). In this case, the intended immigrant has to be single.
Unlike children of the U.S. Citizen, there is no upgrade or downgrade opportunities for children of Legal Permanent Resident after they are married.
So he will lose his eligibility when he is married.
Pick the choices.
2011-05-08 16:30:15 補充：
A whole different story.
Let's say #2 above still applies and still he is sponsored by his mother who was a Legal Permanent Resident at the time of application.
The mother can in fact request the upgrade of the petition from F2B to F1, which will shorten the waiting time for 1 year.
2011-05-08 16:34:31 補充：
Then in theory, as you can upgrade the petition, you should be able to downgrade it as well. So the mother can also request the downgrade and add you in the original petition from F1 to F3.
However, it is a catch:
1. I have suggested this method several time, but no one tells me if it work or not.
2011-05-08 16:36:25 補充：
2. In theory, the NVC can reset the priority (start from the beginning).
So what your boyfriend should do is - request the upgrade first.
Also, contact the NVC to confirm if it can be downgraded (and include you), as well as the reset of priority date.