This really pisses me off. Just state your opinion and give me advice please?

Okay, so my boyfriend and I have been going out for almost 3 months. About three weeks ago, I met his mom on her birthday party, got her a nice and expensive gift (she's really rich), and she seemed to like me a lot. The only bad part about that night was that at the house my boyfriend and I were fooling around and then she asked my boyfriend to come downstairs. Because it took him a while and because she overheard it when I asked "Do you think she's gonna find out?" to my boyfriend, she found out that we were fooling around, but my boyfriend said she liked me a lot, and that she wouldn't fake it if she didnt like me or if she thought I'm a whore. Anyways, I thought she really liked me. So now my boyfriend is leaving for his homeland Germany for 6 weeks, and he will have an internship and he'll sail and stuff. His job will be done in 6 weeks, but his mom wants him to stay there the whole summer. When my boyfriend told her he doesn't want to stay the whole summer, his mom was like "So you're giving up Germany and sailing JUST FOR A CHICK?" And then they argued. I talked to some people about it, for example a friend of mine said that foreigners who come to our country think they're so cool and stuff, and she probably thinks that our relationship isn't serious (but actually I make my boyfriend happier than she had ever managed to and he already started making future plans). I fear that she thinks I'm this loser girl who her son ***** and then is gonna leave, and she doesn't think I'm important or something. Can you please tell me what you think of this situation, what I should do if possible? Thanks a lot.