Is it permissible for a partnership colleague to terminate the contract and request the abandonment of the premises after a year and a half of paying half the costs, and can that be refused?

The majority of scholars hold that a partnership contract is non-binding, and your partner is permitted to dissolve the contract. Your colleague is obligated to return your capital and your share of the profits, if any.

Regarding the shop, if you both did not agree on selling or dividing it, then division takes precedence. Division is of two types: division by mutual consent (which requires the consent of all partners if there is harm or compensation involved) and compulsory division (which does not require mutual consent if there is no harm or compensation).

Your partner is not allowed to take exclusive possession of the shop without your consent. If the shop is large and can be divided without harm, your colleague is compelled to divide it. However, if it is small and would result in harm or require compensation, then the shop must be sold and its price divided between you, and neither partner is allowed to claim exclusive possession of the shop without the other's consent.