Viewers of the show have also noticed the obvious difference in affection shown between the pair with the 24-year-old displaying a much higher interest than the 30-year-old former Wallaby. Fans are now fearing that Cassandra will be left heartbroken when the time comes to leave the show.
Speaking exclusively to Daily Mail, sexology expert Dr Nikki Goldstein suggested that there appeared to be an "element of guilt on Nick's part" when it came to his decision to keep Cassandra on the show and in the competition.
Two convincing reasons were offered up by Dr Goldstein as to why Nick has given Cassandra a rose during each ceremony even though there was an apparent lack of chemistry between the two.
"The first [theory] is that it isn't Nick's choice, and the producers are telling him to keep her in the competition because she has a strong storyline," she explained.
"The other, and more likely, option is that there is an element of guilt on his part, and he's being nice to her and trying to do the right thing by her this time."
A big question surrounding the pairs previous relationship is weather or not the two had sex. Dr Goldstein studied their body language and came to this conclusion: "They definitely hooked up [in the past], if not slept together,"
"There's nothing unusual about that in today's dating culture where young people are often quick to jump into bed with each other... I mean, did they even "date" as it's been claimed? They could have just hooked up a few times."
Meanwhile, Cassandra has remained silent on the extent of her physical relationship with the Honey Badger, but has admitted to going on several dates with him. She is also on friendly terms with Nick's brother Jacob and has met the rest of the family too.
"Perhaps she wasn't the one who ended things," Dr Goldstein suggested. "I wouldn't be surprised if it emerges later that it was a casual hook-up thing and she was left with a crush but he wasn't interested in taking things further,"
"What is clear is that Nick is being a stand-up gentleman on the show. He has kicked out the bullies, he is looking after these girls, regardless of which ones he is most attracted to. That's why Australia has fallen in love with him,"
"Because he is such a stand-up guy, I don't think he would be the type of person to kick Cassandra out [of the mansion] straight away just because he doesn't want a relationship. He's being considerate,"
"Perhaps he understands the show's high profile is a good opportunity for her and that she will get a sympathetic portrayal and so is keeping her around."
Dr Goldstein also believes that Cassandra won't make it to the Bachelor finale, saying, "If you look at the chemistry he has with someone like Brooke, that is genuine mutual attraction. We don't see that with Cass, where all the attraction is coming from her side."