Looking like 2 sisters

"So Serge, what do you think of me?" asked Clem to his best friend.
"You are ... magnificent," replied the young man with sincerity. Alex will be speechless.
- Thank you"
An embarrassing silence settled a few seconds before being abruptly interrupted by Aline, the mother of Clem:
"Hey Serge, don't you think we look like 2 sisters?"
Aline took her daughter in her arms. Indeed, the two women resembled each other very much. It was more than obvious as today was a Youth Day.
"Can you take a picture of us?" asked Aline
Serge complied.

A few minutes later, Clem left her house into the arms of her new boyfriend, leaving her best friend and mother.
"I'm sorry for my daughter, I see her coming out with a lot of guys but she does not realize that she always had the good one at her side.
- What ?! But I... I'm not, stammered Serge.
- Ah ah ! You thought I had not noticed how you looked at my daughter since you were in primary school? "
Serge was finally obliged to admit his love for Clem. After half an hour of confidence on the sofa, Aline stepped softly towards him, his eyes a few inches from the young man. He began to blush.
"I see I'm disturbing you," Aline said, smiling, "you know, if you do not have the girl ... you could have the mother ... Just for tonight, just for fun ... She will never know"
The proposal surprised Serge, who then wondered if Aline was serious. And if so, what should he do?