A Wave is symbolized as one of the strongest forces on earth (Strength). also if you read more into it, its about faith, a wave is you against mother nature, you cannot control it, you just have to put your faith into her.
Two hearts joined together by a cross--symbolizing Christ being the center of the relationship. Also a visual representation of Christ completing each of us individually, as well as bringing and keeping us together.
I think out of all the memorial tatts I have found, this saying stands out the most to me."If love could have saved you, you would have lived forever." If I were ever to get a tattoo, this quote would be it, with the initials M.