Find lines from one file in another

[tester_V]

I really appreciate your help!

I see your point but your code does not have an "else" statement.
I need it, I need to process lines that do not match.
I can print lines that are matched. The iteration in Python is a horror story.
I'd like to repeat, I do not have(by now) finding or matching lines, I have a problem printing those that do not match.
Here is a try 234 of the script:

fout = open ('C:/Scripts/sometext.txt','w')        

with open ('C:/Scripts/Python/CurMACs.txt','r') as cur_fl :        
    cur2 = cur_fl.readlines()
with open ('C:/Scripts/Python/Matched_MACs.txt','r') as m_file :     

    for m_line in m_file :
        m_line = m_line.rstrip()       
        sp_m_line = m_line.split(",")
        m_ltof = sp_m_line[0]+","+sp_m_line[1]  
        for cln2 in cur2 :
            cln2=cln2.rstrip()
        #    print ("Current Line file -->> ",cln2)
            if m_ltof in cln2 :
                #print ('Found Matched line -- ',cln2)
                new_n = cln2+","+"Online"
                print (new_n)
                fout.write(new_n+'\n')
                break

               # else :
               #     print ("OFFLINE !!!!!",cln2)
               #     #new_off= cln2+","+"OffLine"
               #     #fout.write(new_off+'\n')
               #     break
fout.close()

I tried to move the 'else' block all over the place wrote a countless number of snippets and still cannot print the lines that do not match..