B737 Captain reported ATC issued go around instructions on short final due to less than required spacing behind a preceding heavy jet.

Narrative

During normal arrival phase in weather ATC vectored us behind a 777 to intercept the final approach course at 2;500 feet outside of ZZZZZ; cleared us for the approach; and instructed us to maintain 180 IAS to ZZZZZ1 (FAF). As PM I noticed the decreasing range to the heavy aircraft in front and instructed the FO (First Officer) (PF) to start slowing 2 miles early; however on switch to the Tower the Tower Controller told us the separation wasn't going to work and directed a go around at approximately 1;400 AGL to 2;000' and runway heading. We were IMC almost the whole time. FO did a great job and the GA and subsequent approach were normal.Cause: It was a rainy; windy; low visibility day in the area. Approach Controller put us in a high workload corner and the Tower Controller made the GA call since we were IMC. The obvious mitigation is more separation with heavy 777 traffic. It just didn't work today for an approach however we had fuel and time on our side. I could tell the strain on ATC is starting to show. They remained professional and noticeably measured in tough conditions.