When a member buys a subscription, someone has to be the seller on the card statement. That company is the merchant of record. It is responsible for collecting and paying sales tax or VAT, handling refunds, and dealing with disputes from banks.
In app stores, Apple and Google act as merchant of record and take a commission. On the web, a dating company can be its own merchant or use a provider that takes that role and the risk that comes with it.
Dating is often classed as high risk by payment providers because of chargeback rates, which makes payments operations a specialist job.