Losing weight for anyone but yourself never works, whether it be guy, friend, family, etc. It may "work" temporarily, but not in the long run. It's something you want to do yourself, for yourself, nobody else, regardless of how cliche.
I understand completely the feeling of wanting to lose weight for a guy. But... in the long run, it turns on you.
As for becoming bulimic... run as fast as you can away from it. It won't do you any good. It'll damage you quite quickly. Besides what it'll do you physically (hair falling out, teeth falling out/needing pulled out at a young age, skin, heart arrythmias, death, etc.), it is extremely wearing mentally.
You'll start out thinking you can control it, stop any time you want, but in reality, it will begin to control you (I feel like a textbook). Before you know it, you'll be doing it every day, multiple times a day, skipping things you enjoy to stay home and binge and purge, it'll start iterferring with your responsibilities (ie stop going to school, work, etc.) so you can stay home to binge and purge. You start spending every penny on food and then after your bank account is overdrawn, realize you still have to pay your rent/car payment/insurance, etc.
In fact, while, yes, you
can lose weight with bulimia, you can also maintain or gain weight with it. For as many people that lose with it, the same number, if not greater, will maintain their weight; For as many people that lose with it, the same number, if not greater, will gain weight.
Like you said, some situations you do need to find out for yourself, but some things just aren't worth it (ie your body/health/sanity, especially).
I hope in the end that you decide to do what is best and healthiest for you.