It depends. You need to prove that you are or have been living together. This can come from a variety of sources, including a tenancy agreement, but not necessarily. Suitable documents are clearly stated on section 5 of the guide to supported documents here:
https://assets.publishing.service.gov.u ... -04_KP.pdf
There they say:
We recommend that you send at least 6 items, from 3 different sources. These
can be addressed to you jointly or individually, provided they clearly show that you live, or have
lived, at the same address.
The tenancy agreement you mention could have been helpful, only if you supplied another document as well, dated around the same time, addressed to you to the same address that appears in the tenancy agreement.
So to answer your question, provided you sent another 6 documents addressed to you, jointly or individually, to the same address, dated around the same time, you should be fine. It you did not, then you can get your application refused.
My posts express what I believe are the facts, based on the best of my knowledge, about the topics discussed in this forum. They do not constitute immigration advice.