Accidents happen, @Ayman5 and people react differently as you pointed out the difference between the boyfriend and the booking guest. Unless you think there is malicious intent, perhaps it is best to take your personal like or dislike out of the equation and just address the damage and security deposit claim process, i.e., professional and neutral. Also, as you have pointed out, you need mattress protection. You also might add a rule that food is not allowed in the bedroom and should only be consumed in specified areas.
Some misinformation in this discussion thread: Neither Air BNB host protection or access to the security deposit can be applied for "rule breaking". Only verified damage can be claimed. If the damage is related to rule breaking, then add that to the review.
Under the Air BNB sysem, the security deposit is never taken in the first place and therefore will not be "returned" at the end of the reservation. So avoid adding any misleading information in your listing.
As to cancelling and asking for relocation based on what you think might be damaged, I think you are on shaky ground. Again, accidents happen and unless you think malicious behavior caused it, you should just continue the booking. Be sure to document not only the damage but also the conversations you have had, summarized them in the Air BNB messaging system in case you need to prove guest responsibility.
