Love Clock Widget Pro

Never forget the start date of your relation and how long you already stay together.
Call her/him anytime with just one click.
Configure a picture of her/him and see it anytime on your home screen.

Installation of the widget:
Long press on any empty space on your homescreen (a long press will last a couple of seconds). You'll then notice the Widgets option just as you would with the longer method. Click on the widget menu then click on the widget you want to install, this will place your widget on your Android home screen.
On HTC phones you can also use the + button at the bottom right to add widgets. You can see it highlighted in this screenshot. The rest of the process is exactly the same.