Another thing I was going to mention. Perhaps try a tandem. Both you and your BF ride together at the same speed.
Presumably most of the time he would be steering, but it may help you get used to and comfortable being on the bike.
Some couples love their tandems... Others have troubles getting it to work for riding together. But, you certainly will learn a lot about each other.
There are cheap tandems available for less than $500, and used, maybe $100 to $200. That would allow you to just try it out, then if it works... the sky is the limit.