i dont think that telling the OP that they need to buy new equipment to get better is the right approach, im sure their lens are adequate as ive looked through her flickr and noticed some decent shots. What OP needs to do is lower the aperture so the couple is more in focus and the background is not, create more bokeh.
Also these shots look very very posed, i was reading in the proffesional photography forum, notice reading not posting

, and they were saying that when taking pictures of couples and stuff like this, tell them to do something funny, like "bite each others nose", and that way you get real genuine shots, not these were their heads are angled just the right amount, and their smile is overly cheesy.