My Sister Wants To Snatch My Boyfriend

I'm a in serious dilemma right now and it has to do with my boyfriend. I'm presently dating a very sweet and cute guy, who works in an oil company.

My boyfriend loves me so much, and I also love him dearly. We're not a perfect couple though, but we're always able to handle/resolve our differences maturely.

And the success of our relationship is making my friends to be envious of me. Because they've been in and out of several relationship, and are presently sober and desperate for love, and to make the matter worse, my younger sister who just broke up with her guy, is also eying my boyfriend.

Now, it's me against them. They want my fine, rich and loving boyfriend, and are hell bent on snatching him from me.

What should I do?