Jealousy stinks and is never, ever, healthy or good for a relationship. If he doesn't trust you to ride with others, there's more issues than just who rides with who.
That said, you also have to be open to ways to spend time with him. If you spend more time with others than you do with him, it's reasonable for him to say "what the heck?"
It's all about balance, being true to yourself and allow him to be true to himself. You have to know how to compromise, but I think the give and take of a relationship is something you always have to work at.
It's funny how many people meet and fall in love and then spend years trying to change the things they don't like about the other person. That just doesn't work. I guess that's why the vows say "for better or worse".
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"I never made "Who's Who"- but sure as hell I made "What's That??..."