My other half wants another dog?

last year my fiance brought me a 3 year old beared collie (brian) for my birthday we both total love him but he is all me i cont move anywhere without him following me and he only does what i say.Now my fiance wants to get a puppie and as brian is the only dog he has ever know en im sure il have to do everything. Im also worried that brian could become jealous and stat acting . Im not sure i could cope with a puppie but my other half always gets what he wants. If we did get one it would be well looked after and loved. im just so confused in what to do.