Google ranking help with some specific keyword

[anik07bd]

I have a website and It's address is: http://datingindustrysupport.com. I am doing SEO for this website with 3 keywords. They are: Buy dating profiles, Purchase dating profiles and Dating profiles for sale. Before some days I have noticed that, my website ranking is getting good with only one keyword of those but not so much good ranking with the another two. My website is now in Google 1st page (top6) with the keyword of Purchase dating profiles but the another two are now in Google 4th and 6th page.
So in this case what can I do with this two specific keywords for better Google ranking? I need good suggestions. Please help me.
-Thanks.