Heather Corinna replies:
There's this guy at work who keep hitting on me. At first it seemed like innocent flirting but it's gotten downright vulgar and creepy. He's 15 years older than me. I'd like to remain friends with him, if possible but he seems to think that when I turn 18 it will be okay that he says completely inappropriate things in the workplace. I'd rather not file a complaint but I will if I try everything you tell me and it doesn't stop. A friend also suggested that I drop his girlfriend a line through email letting her know what's going on. I think that would be kind of mean and may even make him violent. He's really pushy so it scares me a bit. I'd like to know how to convey to him to knock it off without hurting his feelings or getting anyone else involved.
Why would you want to be friends with someone you feel afraid of and who is harassing you? Who you fear may become violent if you take any action to stop his harassment? That's not the way friends treat each other: this guy is not your friend, and clearly has no interest in being your friend.
Sexual harassment at work is serious business: it's against the law and the people -- mostly women -- who fought to make it so fought long and hard. Loads and loads of people before sexual harassment laws had no recourse: you are lucky enough to have it now. The reason why it's serious business is because you're entitled to have a job and to be able to do your job without having to fend off sexual advances while you do it. You're entitled to a safe workplace where you are treated with the same respect you afford your co-workers.
Worrying about hurting his feelings also isn't sage: believe me, someone who is sexually harassing you couldn't care less about hurting your feelings, and if he was being made to feel the way you are, and within the same kinds of power imbalances, he'd do something to stop this without thinking twice about it. More to the point, someone's feelings are not more important than your personal safety and security, especially when that someone is the person endangering you.
Really, I'd encourage you to file a complaint with your workplace now. It sounds like this has already been escalating, and is already an established pattern of behavior, which means it's time for that. It's not sage to wait until someone assaults you or gets you to the point of having to consider leaving your job to file a complaint. Too, the longer you wait to complain, the easier it can be for someone harassing you to claim that you were just fine with it, even though that's not fair. You just can't be passive when you are being harassed: you need to stand up for yourself.
But if you want to do something before you go there, don't do things like emailing girlfriends. You're at work, and should handle this professionally. This isn't a game or a soap opera, and when it's clear you are acting professionally, it makes it all the more clear that the person harassing you is not.
So, one thing you might do before you file a report is to simply type a formal letter, or send a formal email to him which includes your workplace's policies on sexual harassment (or details your federal or local laws about it: if you're in the United States, you can see the basics here), explains in detail what he has done to you, and makes clear that you are asking him to cease his behavior immediately, and if it does not cease, you intend to file a complaint with your employer. Do yourself a favor and keep a copy of that letter -- on your computer as well as printed -- on file. You may need it later if this continues to support your claim. That letter in and of itself may solve the problem: when a person is clearly assertive and not passive, and clearly prepared to take action, it can tend to make them an unappealing target for harassment and abuse: overall, people who harass and abuse are usually looking for someone to harass who they perceive as helpless or without power.
If you're trying to be friendly with him, I'd also suggest you stop doing that. However you have to interact with him when it comes to your job, go ahead and interact in those ways. But don't talk to him casually, sit with him at lunch, chat with him on breaks, etc. You need to cut off any and all contact that is not expressly about doing your job. You may also want to inform another co-worker you feel safe with about what is going on so that they can keep an eye out for you as well, and help to keep this guy away from you.
If after sending that letter the behavior doesn't stop, then you really need to file a formal complaint. Remember, you're not the one who should feel embarrassed or meek here: he's the one behaving badly and unlawfully. As well, your workplace owes every single person who works there a safe environment, so asking for their help in this isn't asking a favor, it's asking them to do what workplaces are supposed to be doing, by law, for all their employees.
Here are some other online resources for you about sexual harassment: