I do think Leo had an ulterior motive for getting together with Skye. Either he know she was popular and thought hooking up with her would get him popularity, or he knew a showmance was his only hope of survival as an intruder, and Skye was the only single gril.
But when you think about it, Skye is just as bad. She was really into Jake in the first few weeks, even it meant risking an argument with Lisa. She was quick to move to Leo once Jake got the boot.
Then there was the whole thing with Ryan. Remember she didn’t like him and called him condescending? That was the week when Ryan had been nominated for the first time and Skye didn’t know he had such a big fanbase. After Ryan got most saved, Skye panicked and proceeded to nominate him because of it. I think she though that because she was so popular, Ryan and Sandra would get booted for trying to take her on. Which didn’t work in Ryan’s case.
Then when Leo was up for eviction against all the original housemates, the majority of people on this forum thought he was most likely to go, and Skye probably had the same viewpoint. That was the same week when he was in the sanctuary and she started announced her change of heart with regards to Ryan.
My theory is that she thought “Hang on a minute. Ryan was most saved, so he must be massively popular and I don’t know if I can beat him, so why not try to mend fences with Ryan, so that his big fanbase on the outside don’t vote against me. Leo is going anyway so it won’t really matter what he thinks”. Michael used a similar tactic in 2012, when Estelle kept getting saved every week, he realised she must be hugely popular and suddenly decided that he didn’t hate her anymore and wanted to be cuddle buddies. Although that one backfired spectacularly.
It is already a known fact that Skye was concerned about Ryan being the most saved, as she even nominated him for that exact reason.
The plan went pear shaped when Lawson, Cat and Aisha got evicted and Leo survived. Just look at Skye’s reaction each time Leo has been saved and you will notice that she doesn’t seem too happy (same happened again last night). She can’t really make a move on Ryan while Leo is still in there, because he could make a big deal out of her cheating on him and therefore screw her chances of winning.