As flight attendants will tell you, put your own mask on first, then put the mask on your child.
I understand wanting to give to others. I really do. My wife and I love to give each other what the other wants. However, we also don't ask for something that is not affordable. One of our gifts to each other is living debt-free. During our 14 years of marriage, we have almost never fought over money. We have a budget, and we stick to it way more often than not. When we need to replace our Lexus, we will pay cash. There is a tremendous mental freedom and lack of worry that comes from living this way.
If you have other debts, you really shouldn't buy this bike. You currently have student and car loans. You should pay those off before getting into more debt. What temp job is this that will pay so well - Pottery Barn? If the economy continues getting worse, and you lose your job, what if there is competition for those temp jobs from all the other people that lose jobs? Hope is not a plan. How will you pay for your car and your student loan? Are you going to live with your parents your whole life? Won't you one day want to live on your own? If you had no car loan and no student loan, perhaps you wouldn't have to live with your parents now.
Some women want to move straight from living with their parents to living with a new husband. If that is your plan, I encourage you to re-think that. It is good for your personal growth to live on your own for a while.
What makes you so sure this boyfriend will not leave you? Isn't that what everyone always thinks? It is all too common for women to end up dependent on men for their financial knowledge and security. Then what happens when the husband leaves his wife of 20 years, and she has to raise the kids while he is on to his second, younger wife? Seriously, think about this. I know many women who have been left in bad shape due to this. Learn to be smart with your money now. Don't wait until you are broke to figure it out.
If you will get the bike sooner or later, get it later. When you actually have the money.
Does he want you to buy it for him? Why would someone who claims to love you want you to go into more debt just to buy him a bike that he is not willing buy for himself? How about this, would he buy something like that for you?