I think stukje added "d'amour" after "je t'aime beaucoup" just to put the stress on the love relationship between sender of the message and the addressee, and in order to differenciate it from a simple friendship relation.
I'll replace "je t'aime beaucoup d'amour" with "je t'aime tant" ("tant" : "so much"
Here in the English version "beautiful" is to be replaced with "good".