How cruel is deliberately lying about wanting marriage and kids just to get a girlfriend?

From a 1-10 scale, how cruel and mean would this be:

A man enters a relationship by deliberately deceiving a marriage-minded woman. He knew from the very beginning she doesn't want to be a man's girlfriend for 4+ years.

The woman breaks up when he later on admits (he had no option but to tell the truth because the woman didn't agree to move in with him) to only going along with her just so she can stayed being his girlfriend for a bit longer. She's still young in her 20's but this was a total waste of time for her. This earned him not just a break-up but being blocked too.

Honestly how cruel is entering a relationship with a lie because you knew they would've never dated you if they knew the truth from Day 1?

Updates
2 mo
It's one thing to continue dating someone that doesn't share your goals (if it doesn't work then it's your fault for staying) but another to date someone that lied just to keep you.
How cruel is deliberately lying about wanting marriage and kids just to get a girlfriend?
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