So what you are doing is comparing EasyJet fares on the IOM-LPL with Flybe on a different route altogether. That is not how fair comparisons work.
1st feb is next week, that is not booking in advance. Having looked at this again there are return fares of between £70 and £80 at the end of feb (4 week booking time) which whilst more expensive than the LPL route is stll lower than that being quoted.
Unfortunately if you are tied to certain flights and are inflexible you will have to put up with fares changing and getting higher. Unsurprisingly this is the same with Easyjet fares across their network (beyond their single IOM route) You are just being unfortunate as a result.
Whilst Tinwald is pleased to have competition, EZY wont stay on the IOM. The airport has already said that pax numbers are down, and this is not because of fares or limited destinations. There is not enough demand and this means its getting harder to fill up planes - especially A319s