As excuses go, this is very poor, but as long as she can find any reason to say 'no' to you, this is what she will keep on doing - why? Well there is no exciting build up. Think of how many times you have had sex with this person and are going to in the future. It can't always be random, sometimes there has to be a narrative to lead to sex, to make the whole experience exciting. I know what you're thinking, as men we don't need this, but oblige your ladies. Read a romance novel aimed at women and realise that the sex is the conclusion to a massive prologue of interaction first.
THE SOLUTION: Romance. Think of a way to court your partner, with the finale leading to sex/love. But even after the deed, keep up the narrative so it becomes a cherished memory. Obviously we can't always do this in life, but every so often, a narrative will add spark to the proceedings and let her know that she is appreciated.
House work is tiring and sometimes endless. By the time you have got one thing done, there is another chore waiting for you. It's monotonous, it's boring and it's constant. After a day of doing this and wanting to just rest, a segue into sex may be the last thing on her mind.
THE SOLUTION: HELP HER! Yes it's that simple, help your partner with the chores, let them know you are a team and that you appreciate what they do. Having your partner's back will bring you closer together and make your bond stronger...hey, sex may happen as you actually do the chores together!
Either she feels un-sexy and unmotivated to be so or she is deliberately making herself unsexy so you won't want her. Either way, what she wants is love and affection in her life and these two elements can't always be given as a bridge to sex. The cuddling comment is vital clue to the loving part, as you can cuddle intimately and not have it precede sex. Love her without sex being part of the bargain.
THE SOLUTION: Create dates and situations where you have to dress up and be elegant, don't take her to the cinema, take her to the opera or a place that requires you to be sleek and stylish. In and around that, treat her as if you've just met her, where that spark of lust, desire and love was at its highest. Adore her accordingly and remember although it has its place, routine can be the protocol of the dull!
Since when, could you not have sex during the week? The answer of course is never! Thursday's problem is a cross between Monday and Tuesday's scenario. Access and the desire for sex is cultivated through everything you do in your relationship to garner reverence and appreciation. 'It's a school night' may be a reference to having so much to take care of independently of your help during the working week, that once again she is knackered and doesn't feel like doing anything...well anything with you. She may even resent you for not understanding how she feels in the first place.
THE SOLUTION: See Monday and Tuesday's remedy...
This is 'fob off' sex. Just to get you off her back, your partner is willing to lend her body to you, to either shut you up or momentarily satisfy your desire, this is not a good situation to be in. She doesn't want to have sex with you, but she might feel the tiny tiniest guilt for depriving you.
THE SOLUTION: You have to make sex be an event again for the both of you. New moves, role play, dressing up - whatever gets her and you going has to feature. You can't go straight into this though, you have to go through some or all of the remedies mentioned first from the other days of the week. When things get better, you can then have a conversation about your sex life and let the fun and games begin.