I do think that Morgan and Garcia care deeply for one another. Notice how jealously that Morgan reacted when Garcia got that date with James Colby Baylor in Season 3, and how Garcia couldn't handle the jealousy.
Well... personally, while I agree he was jealous, I don't think it was because he saw James as a rival for her romantically speaking. I think it was because Garcia is always there for Morgan when he needs an ear or someone to talk to him (like in the season premiere when he told her not to ever stop talking to him) and he was afraid that if she got a boyfriend outside of work that she wouldn't always be there anymore. I think the two are best friends and sometimes best friends get jealous when their friend gets a bf/gf because that's less time they'll get to spend with them. If he's jealous of Kevin in that way, he doesn't show it because of how badly Garcia handled his jealously the first time around. But, I honestly do not think the jealousy was because he wants her for himself. However, that is just my opinion.