When Matti begins to fall for Alona early in Season 1 of the show, it's shown that Dina doesn't have any interest in interaction with Alona whatsoever, even offering to help Matti get with Alona, through different strategies, which ultimately come to no avail.
However it could be implied that Dina does have feelings through this very fact alone, and as such this has made Dina uneasy around Alona, as secretly Dina has feelings for Matti. When Alona disappears after the Israeli space shuttle failure, Dina is quite openly suspicious about Alona's disappearance, however she still helps Matti to find out where she has gone.
Later on in the season, when Dina discovers what's happened to Alona, she's quite concerned about Alona's situation, alongside Matti and receives help from . When Alona later returns to the Greenhouse, joining up with Team Galapagos, Alona and Dina bond while working on helping the cause to stop Ze'ev. Eventually Alona notices how much Dina and Matti have bonded, during the time she was away and steps back in the end.
Both Dina and Alona return in Season 2 of the Greenhouse, both taking part in a hiking/team-orientation task in the mountains. When Matti manages to injure himself during the task, both girls help him up, clearly showing each still had feelings for Matti. This is further shown when they are at the hospital, while comforting Matti, who is in his crutches. Matti is clearly shown to enjoy joking around with Alona during this time, which only makes Dina more jealous, as Matti is falling back in love with Alona again, although she clearly denies this fact.