In an interview with New! magazine, the 'Made In Chelsea' beauty revealed the pair said those three little words after only a few weeks together.
"We were in love very early on in our relationship. I think we had only been going out for a month," she said.
She added that the pair have even discussed their long-term future.
"We talk about the future in a promising, optimistic way," she said. "We joke about being married, what our kids would look like... They'd have good genes but enormous nostrils!"
The pair went public with their relationship earlier this year after Louise split from co-star Spencer Matthews, following his infidelity.
However, they hit a bad patch after Louise spent the night partying at One Direction singer Niall Horan's house, leaving Andy devastated.
"I'm just gutted," he said at the time. "I don't know how she can so casually do it to someone else, she knows exactly what I feel like."