I'm not an expert on French rail fares, but that sounds high to me. I wonder whether you're looking so early that the promo-priced tickets aren't loaded yet. You'll almost certainly pay extra buying from Trainline rather than directly from the French railroad, SNCF.
I just looked at Friday, July 1, and found adult fares ranging from 39 to 89 euros. I would certainly not buy tickets from Trainline at that price without doing more research.
Please give us your travel date so the folks who are knowledgeable about booking French trains can give you more specific input.