It depends! Normally, the percentage that you can save with that EHarmony Coupon will be shown right on the page, so you can see if it is applied sitewide or not. However, once you are not sure, try it right on their's products you want to buy.

Usually, Coupon Stacking is not allowed at EHarmony. However, the store will surely give out notice if available.

Yes. Coupons for each Discount Event of EHarmony will be collected here while being updated day by day. Sometimes, there will be deals not updated promptly but it's rare, we expect sympathy from you. 

Our advice for you to use EHarmony Coupon effectively is to choose the right day.
Like thousands of other consumers, the time of promotion is when they choose to
shop at EHarmony, so take advantage of coupons released on those days to save.