When you find your dog is in love, enjoy the moments, and host a dog wedding. It can be a fun affair, and you would of course invite all your friends who have dogs.

[edit] Steps

Go to a pet store and find some clothes for the "bride" and "groom". If you aren't able to find something that will work, make an outfit or have someone else make one.
Find a tiara for the female dog.
Set up a dog sized wedding place. Many people enjoy having doggie weddings in their backyards, or even the beach!
Make an isle. You can use some sort of fancy fabric or you can just use an old rug.
Invite some of the couple's favorite dog friends to the wedding.
Have the dogs "come" to walk down the aisle. Now onto the vows: Say something nice about the dogs and how you hope they will be happy together.
Have your dogs jump through a hula hoop to complete the "double ring ceremony".
Pronounce them married!

[edit] Tips

Don't go too overboard.

[edit] Warnings

Make sure the dogs are ok with this. Wouldn't want them divorcing!
Your dogs are not people! No matter how much you may love both dogs and think they are exceedingly intelligent, they do not understand the concept of getting married. Keep in mind that this ceremony is more for the people involved than the dogs. Don't be disappointed if the "bride" won't wear her tiara, the "groom" takes a sudden interest in another dog and won't come to the "altar" or the whole thing is just a total fiasco.
Not everyone may be as excited about a dog wedding as you are. Don't be too disappointed if some people decline or give you weird looks. Try to determine beforehand which people will actually enjoy a dog wedding and which will wonder if you're serious.
Be considerate of your neighbors. If the participants and guests get too loud, you may want to cut the celebration short.
In some countries such things are not allowed, so check the laws before you host a canine wedding.
Don't care what anyone says, it's your animal.