Muscle makes almost no difference in dating
As someone who has been both skinny and muscular I’ve never noticed any difference in the amount of attention or ease of dating after gaining muscle. Unless you are extremely malnourished it won’t help much. Most women just date guys in their social circle that they get along with. They don’t even notice or pay attention to buff dudes.
No guy struggles to date because of lack of muscle. Plus whatever is causing him to struggle will still be there after getting jacked. You are better off finding a good friend group/social circle or going to therapy.