It depends on lot of things.
It is imperative to know whether your wife is working lady?
Is she suffering from any sickness?
Has some thing unwanted things happen in her family?
How your children are doing in school?
And regarding you , sex life depends on certain factors.
When do you return from Office/factory/workplace?
Do you extend the hands of cooperation to your wife in her kitchen work?
Do you drink or smoke heavily?
If a person is given some of the above informations it will be better to advice.
Any in general you have to act i.e. love play and try to arrouse her, change the position,
Besides try to love her besides the sex.
After all sex is not only criteria in family life, but no doubt that is vital.
Better to consult a doc.
Since you have mentioned it is boaring, that means you have your own problem. And may be you have started not liking your wife.
It is therefore suggested you must change the position and extend the love play for long time. And try to think positive.