I was hoping to get a response back to my request for more information before answering, but I do realize that this is time sensitive. Let me go over the mating process and the heat cycle.
A few key things is that the female needs to be in the right stage of heat and also needs to be brought into the males territory for mating and not the other way around. Male dogs become sexually mature around 6-7 months of age so unless he is younger than that he is old enough. Now the problem is that if you own both dogs then it is possible your female is the dominant dog and she won't be so inclined to let him mount her as it is a dominant behavior.
To breed successfully you need to understand the heat cycle. I have explained it below and included a site that has a pictorial guide so there is no mistake what stage of heat your girl is in.
Female Dogs go into heat at any time between 6-12 months usually. The average heat cycle for a dog is approximately 3 weeks but for some dogs it is longer and for others it is shorter. Some as short as 10 days and some as long as 4 weeks or more. Usually your dog will go into heat every 6-7 months though again each dog is different and can go back into heat as early as 4 months or not for 12 months. Most however are average.
During the first part of a dogs heat period you will notice swelling of the vulva, possibly an increase in urination and bleeding. If there are male dogs around you will notice them hanging around her. This stage generally last about 7 days and she will not allow males to mate with her during this period The second part of the heat cycle is when she will accept a male and breed. Usually a female will lift her tail out of the way. Usually bleeding has stopped or become straw colored at this point. This can last from 4 to 21 days though the average is 7 days. Many expert say the 9-10th day of heat is the optimum day for breeding. It is during this period of time that you will want to allow mating. Most breeders allow the dogs to mate every other day during this period.
Then during the last stage of heat she will be less willing to breed as she is going out of heat. This stage can again last from 4 to 21 days as well but averages 7 days.
Each dog is different so some evaluation by the owner is necessary. The whole heat period should be approximately 21 days but as stated can be longer or shorter depending on the dog.
Here is an excellent website with pictures to illustrate a female in different stages of heat.
That said, it is likely too late to establish an area of the house that belongs to the male only. However, you can start establishing that area for her next heat cycle. Just have a room that is off limits to the female and only the male is allowed in. At the next heat cycle, then when she is in the right stage of heat, put her into HIS territory for mating. This will make him more likely to mount her since he would be dominant in his territory. Keep this in mind if she is in the right stage of heat and moving her tail to the side.
Now if it is a case of her being too dominant, taking her to another stud dog's home might do the trick and get her to allow the new male to mount her and mating occur. It does sound like your own male is just not dominant enough to mount her and attempt to achieve a tie.
Another option would be artificial insemination. Most vets do not charge much if the male and female are both there together. Some are as low as $75 but each one charges different amounts so call first and ask for price of harvesting semen and doing the ai at one time. Some breeders do this themselves. Here is an excellent site on this.
And purchase kits from here:
There is also a video on the process as well.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer.