Not sure what routes you are planning to do.

Day 1 - the 75 miler has a lot of rollers. No significant climbs, but repeated rollers. Perhaps 1 - 2 climbs of less than a mile - nothing too bad, though. The 100 miler has a climb, Marshall Wall, done form the easy side. That's probably 1 - 2 miles of real climb, totally doable.

Day 2 - neither route has any long climbs.

For any of the routes it would be really good to get some hill training under your belt to make you more confident and help you work on pacing. I agree with your boyfriend, even though I have never met you, you ARE capable of almost anything. It's largely mental - if you think you can do it, you can.