How much trouble can you get in for giving a minor alcohol?

My friend whose 18 is dating a guy whose 23 (and in the coastguard) went to a party at his house and she said they played beer pong and I asked if she drank and she said no she couldn't so she just did and water and my other friend overheard and her dad is in the coastguard so she told him her boyfriend let her drink (which may or may not be accurate) and so now the dads trynna get the boyfriend in trouble, and I'm just wondering what will happen to him? Will he lose his job? And forever? Go to jail? And what if it's inaccurate will the dad or my other friend get in trouble for false claims?