My two cents': Both of you need to 'ride your own ride'! Your guy pal ought to honor the fact that your approach to a long ride is simply different from his. If your upcoming ride is an organized century, there will be plenty of riders of all abilities to hang with as people sort themselves out over the course of the day.

My BF is MUCH stronger than I am, so when we do long rides together he either 1) rides at my pace and enjoys it as a relaxing spin, or 2) rides at my pace for a few miles and then takes off after giving me a 'have fun!' kiss. I'll be darned if I'm going to move faster than I feel comfortable, LOL!, particularly on a long organized ride where pacing myself is the key to going the distance! Life's too short to be miserable trying to meet someone else's off-the-mark expectations!