Don't let the weekend be your 'weak end". You put in all that hard work this week, don't go 5 steps forward to go 2 back. Decide how important your goals are to you versus eating whatever food you want this weekend or overindulging. No, 1 meal won't ruin your diet but if you're doing this weekend after weekend and the scale isn't budging you need to decide which is more important to you.
Also remember that enjoying yourself does not consist of eating as much as you possibly can. Eat your favorite foods in moderation. If you're going to a party or out to eat obviously you can't weigh your food. Take a picture of your plate so you remember what you ate or if you know what restaurant you're going too, look at the menu beforehand and pre-log your food if you're tracking or know what to order so you're not making bad food choices. And last, deciding not to eat something or drink alcohol at a party does not make you a bad guest. Have a plan at events you're going too and stick to it! Don't erase all your hard work this week because it's the weekend.