If you want this, you have to choose monogamy. Polyamory is antithetical to "wanting you and ONLY YOU forever". Even if you do choose monogamy there is no guarantee that someone else will love you and only you, forever. But it's a lot more possible than if you're having multiple partners. If you can't commit to one person and pour your romantic energies into one person, it's unrealistic to wish for someone else to give you what you're unwilling to give others.