How to translate/understand "还不" in "还不是因为爱"
It's translated as “actually", "really", "just"; it is used to show your emphasis. It's a very tricky expression because it has no negative meaning, while it has a negative look (不).You usually use this word in a sentence as a response to show your disagreement with the speaker.

You and your friends go hiking in a big mountain, and you get lost. Fortunately, you have a GPS device, and it helps you get out of the adversity. When you are safe, one of your friends says, "Thank goodness!". You would say,


  这还不是因为我带了GPS导航仪。= It is really because I took the GPS navigator along.


Here, You imply that he should thank you!Not thank goodness!.

And another one would say


  还不是我叫你带上的。=It's I who asks you to take it along.


Now,he wants everyone to know that they should thank him :)


  还不是因为爱。= (It is) really because of love.


I also want to show you the negative form of this expression, you would say:


  这还真不是因为爱。= This is really not because of love.